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Volume 21, 1888
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Art. XXXIII.—On the Fossil Marine Diatomaceous Deposit near Oamaru.

[Read before the Otago Institute 12th June, 1888.]

Plates XVIII–XXIII.

Considerable interest has been excited in scientific circles throughout the world by the reports of Messrs. E. Grove and G. Sturt on the deposit of diatomaceous earth found at Cormack's siding, near Oamaru, which were published in the “Journal of the Quekett Microscopical Club.”*

The attention of these gentlemen was drawn by Mr. H. Morland to a specimen sent home to the Colonial Exhibition in 1886, and further specimens were given them by the late Sir Julius von Haast.

It is not quite clear who sent the original specimen to the Colonial Exhibition, neither does it matter very much. Certainly, early in 1886 the late Resident Magistrate here, Mr. H. W. Robinson (now Resident Magistrate at Wellington), received a circular letter from Dr. Hector (now Sir James Hector) asking for specimens of various kinds from this district. Mr. Robinson consulted me on the matter, and I suggested that amongst other things he should send some peculiar earth, which I then thought was a form of kaolin, from Cormack's siding, Cave Valley. My attention had been drawn to this deposit by Mr. A. McKay, of the Geological Department

[Footnote] * “Journ. Quekett Micr. Club,” 16th September, 1886; 17th January, 1887; 18th May, 1887; and 19th August, 1887.

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in Wellington, in 1882, and since that time I have used it for various purposes. Under the microscope I found diatoms in it, but was then very ignorant of the whole subject, and was unaware that any new forms existed in it; but from remarks passed by Mr. McKay I gathered that the earth, or ooze, had more than passing interest, and thus I was induced to give some of it to Mr. Robinson for the Exhibition. Shortly after Mr. Robinson informed me that he had received a report on the earth from the Geological Department that it was not kaolin, but “diatomaceous earth.”

Messrs. Grove and Sturt are amongst the foremost of the authorities on Diatomaceæ in Great Britain. The former some years ago investigated and described some of our New Zealand freshwater Diatomaceæ sent to him by the late Mr. Inglis, of Christchurch.* These gentlemen at once recognised the richness of this deposit, and ascertained the presence of a number of forms new to science. In their papers and reports referred to above they give a description and list of 283 forms, of which 107 are new species or varieties. They also have discovered four new genera—Anthodiscus, Kittonia, Monopsia, and Huttonia, the latter named after Captain Hutton—and a new sub-genus, Pseudo-rutilaria. Since then other samples of diatomaceous ooze from other localities—which, as I will presently show, vary considerably from that at Cormack's siding—have been sent to these gentlemen; and I have no doubt but that the list of species will be much extended.

In their first communication Messrs. Grove and Sturt note that the deposit consists “mainly of diatomaceous remains, with a small proportion of Radiolaria and sponge-spicules:” and they call attention to the interesting and curious fact that several of the forms existing here have previously only been found in the Cambridge Estate, Barbadoes; that others, again, resembled forms found previously only in Simbirsk, in Russia, and also at Brünn, in the fossil condition; and they remark that several of the forms are still to be found living in the Indian Ocean.

Since I commenced this paper I have received from Mr. Grove a very valuable and representative collection of Diatomaceæ from various parts of the world, in which he has taken the trouble to select and mark diatoms found in Japan, Hongkong, Fiji, and Bombay, in the living conditions, exactly similar to those found here in Oamaru as fossils. A slide from the Barbadoes deposit is very similar to one prepared from our deposit; and I have found similar diatoms in ooze gathered in the “Challenger” expedition given me by

[Footnote] * “Trans. N.Z. Inst.,” vol. xv., p. 340.

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Dr. Colquhoun, and also in some diatoms found in guano given me by Dr. de Zouche.

This discovery led to much inquiry, and many were the requests sent to various persons in Oamaru from all parts for specimens of the earth; and I am sorry to say that a great deal of the wrong material has been sent away—perfectly useless. One parcel alone of nearly 2001b. weight contained only one or two lumps of earth containing diatoms, and those were by no means rich.

To obviate this, and avoid disappointment for the future, I have prepared a map of the district (Pl. XVIII.) showing the deposits as far as they have been hitherto found, and the roads leading to them. The deposits are so extensive that there is no fear of their becoming exhausted. One alone at Jackson's is about a quarter of a mile long, and shows a face of some 60ft. How far it goes back I have no means of ascertaining. I have also prepared diagrammatic sketches showing the appearance of the deposits as exposed, and the relation of the diatomaceous ooze to the other earths.

Plate XIX., fig. 1, shows a section of the railway-cutting at Cormack's siding. Here the prominent feature is the volcanic dyke, b, cutting through it; on each side is a hard white earth very similar to the proper diatom ooze in appearance, but heavier and much harder. This is the earth which has been sent home, and which has led to so much vexation. It is more easily collected. Between the volcanic dyke and this hard material there is a distinct line of demarcation, but none exists between the hard material and the true diatom earth; and as a matter of fact the further away from the dyke the richer is the ooze in diatoms and other siliceous remains. Hence I would infer that the intruding dyke has heated and partly fused and compressed the diatom earth through which it has burst. The same condition is found in various other places where dykes exist or where there appears to be a flow of lava, as under Jackson's paddock (Plate XIX., fig. 2b): there, along the road-line, is a volcanic layer similar in its appearance to the dyke at Cormack's, and with the same hard white stuff. At many points in Cave Valley, and in the Waiarekei Valley below Jackson's, Bain's, and Totara, does the same condition exist; and also, in the neighbourhood of these places the plough turns up pure diatom ooze. The diatom ooze, also, at Cormack's, as in the other sub-volcanic deposits, is non-calcareous. Microscopically it is peculiar in the number of a species of diatom called Stephanopyxis present in it, and which may be said to be characteristic of it. Also, this non-calcareous ooze has a much smaller quantity of Radiolaria—i.e., Polycystinæ, &c.—and sponge-spicules in it than the calcareous diatom ooze which is found above the volcanic remains. I have

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endeavoured to show this in Plate XX., fig. 1, representative of Cormack's siding; fig. 2, of H. Allen's. (The sub-volcanic deposit at Bain's is very similar to these.) In these it will be noticed that the diatoms, Polycystinæ, and sponge-spicules are much smaller than in figs. 4 and 5, which represent the forms found in the supra-volcanic calcareous diatom earth in Jackson's and Bain's; also that in the former or sub-volcanic deposits Stephanopyxis abounds, and is absent, or, at any rate, rare, in the latter. Fig. 3 shows a peculiar deposit on the Totara Estate. It is a continuation of the upper layer of Bain's sub-volcanic layers, and lies somewhat higher. I am unable to account for the minute character of the diatomaceous remains found here unless it be a question of gravity, and that the diatom mud was shaken up and the heavier forms fell to the lower depths.

Although the large forms are much more abundant in Jackson's and Bain's, and much more perfect, it must not be assumed that they are absent in the other deposits, for they are found, but only in fragments and scarce. Mr. Grove accounts for their better preservation in Jackson's by the larger forms of the sponge-remains and the great quantity of the spongioliths: the diatom-valves falling amongst them would be protected.

I suggested previously that the hard white material was altered and semi-fused diatom earth—altered by the action of the intense heat of the volcanic lava in the dyke. This theory seems confirmed by the conditions of the layers at Bain's and at Allen's. Here the volcanic remains consist of tuff, or volcanic ash, and this seems to me to have settled down on the diatomaceous ooze in a cooled state, for I find that the white earth immediately attached to the tuff is just as rich in diatoms as any other part of the deposit; and, indeed, some of the tuff is perforated by or surrounds hollows filled up by pure diatom ooze.

I have not yet referred to the Ototara limestone lying above the diatom earth and the volcanic remains, and feel very diffident in putting forth any theory on the geological conditions and ages of the deposits, but I will do so in order to invite discussion and obtain information from those well calculated to give it.

It seems to me that at a very early period of the history of this part of the world matters were very quiet, and that there was a greater excess of vegetable life, and that animal life was then less abundant. This period of rest was disturbed by volcanic irruptions, and possibly the levels were altered. After this disturbed era had passed away a fresh growth of vegetable and animal life followed, but, owing to some change of conditions, the animal life, as represented by the Polycystinæ and sponges,

Picture icon

To illustrate Paper by H. A. de Lautour.

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became more abundant and prolific; then, in order to fulfil their functions in the balance of nature, the Diatomaceæ also increased in number and size; and, finally, that, the conditions being prepared for them, the higher forms of animal life appeared and formed the limestone.

Dr. G. Hartwig in “The Sea and its Living Wonders” says, “Without the diatoms there would be neither food for aquatic animals nor (if it were possible for these to maintain themselves by preying on one another) could the ocean waters be purified of the carbonic acid which animal respiration would be continually imparting to it. Thus it is not in vain that they abound in the most inhospitable seas, where but for them no sea-bird would flap its wings, and no dolphin dart through the desert waters.”

Dr. Hartwig also states that they increase so quickly and multiply by division (other authors say also by conjugation) that in forty-eight hours a single diatom may multiply to 8,000,000, and in four days to 140,000,000,000,000, “when the siliceous coverings of its enormous progeny will already suffice to fill up a space of two cubic feet.”(!)

Many other remains found in these earths are highly interesting, and no doubt are new to science. The Foraminifera are very abundant, especially in the calcareous deposits. I have figured a few, Plate XX., fig. 6. The Radiolaria and Polycystinæ are very striking and beautiful forms. As for the spongioliths, they are so abundant and fine in Jackson's deposit that Mr. B. W. Priest, an authority on the sponges, states that for “size, variety, and quantity this deposit far surpasses any previously discovered.” Dr. Hind, I may add, is preparing a monograph on the spongioliths of this locality.

In examining the various deposits, and in working out various details in connection with this paper, I have received much assistance from Messrs. John Forrester and C. Peach, of the Oamaru Harbour Board. Mr. Charles Gifford, of the Waitaki High School, was, I believe, the first to find out and examine the deposit in Jackson's paddock. Mr. Th. Isdaile, of Enfield, has also given me much valuable information.

With regard to the practical uses to which diatomaceous earth may be applied, much, I imagine, depends upon its purity and the relative quantity of silica which it contains. I regret that I have been unable to get an analysis of this deposit, and therefore cannot give the requisite information. The uses, however, to which diatom earth has been put are many and important, and doubtless many others will be discovered in the future. These, however, have been enumerated by Mr. H. G. Hanks, State Mineralogist, California:—

(1.)

As a polishing-powder diatom earth has long been used in the form of tripoli. As has been remarked, these almost

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invisible organisms give invisible scratches; hence the value of the earth as a polishing-powder.

(2.)

In the manufacture of silicate of potash or silicate of soda—“wasser glasse” or liquid glass. This is becoming a most useful article, and may be prepared by treating diatom earth with hydrate of lime and then with potash or soda. Liquid glass is useful for many things, such as making a fireproof paint for wood, in the manufacture of soap; and is far better than plaster of Paris or gum and starch for use in stiff bandages for surgical purposes.

(3.)

In the manufacture of porcelain.

(4.)

For making cement.

(5.)

As a filtering medium.

(6.)

For lighting fires. Taking advantage of its highly absorbent properties, it is fitted in convenient sizes to an iron-wire handle, then saturated with kerosene. When it is desired to light a fire put a match to the saturated earth and place it between the bars of the grate. When the fire is lit remove the earth and blow it out, and use again when required.

(7.)

A lost art—one known to the ancients—has been rediscovered—viz., the art of making floating bricks. This is done by the addition of one-twentieth of clay.

(8.)

In the manufacture of dynamite and lithofracteur, the first containing 73 per cent. of nitro-glycerine, the latter 69 per cent.

(9.)

As a surgical dressing for suppurating wounds. I have long used it for this purpose. It is highly absorbent and unirritating. I find that 60 grains of diatom earth, quite dry, will absorb in a couple of hours more than its own weight of water. One piece that I tried weighed 60 grains dry, and 135 grains when saturated. I powder it finely and add small quantities of some antiseptic, and dust it over the wound.

Now as to the methods to be adopted to clean and mount the diatoms in this deposit. The first thing to be done is to disintegrate the earth. This can be done (a very slow process) by soaking the earth a very long time in water and letting it crumble, and then carefully washing out the clay. A much quicker plan has been suggested by M. Parmentier, a professor of chemistry in Belgium, and was communicated by M. Guimard to the Quekett Club.*

It consists in the supersaturation of the earth by some neutral salt, and then recrystallizing it. The crystals penetrate in every direction; then, when redissolved, the earth breaks up into a fine powder. More exactly, place a few small fragments of the earth, the size of peas, in a test-tube, and cover them to about 2 centimetres with acetate of soda, and add a

[Footnote] * “Journ. Quekett Club,” Dec., 1887.

Picture icon

To illustrate Paper by H. A. de Lautour.

Picture icon

To illustrate Paper by H. A. de Lautour.

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drop or two of water. The exact proportion is 5 c. centimetres of water to 100 c.c. of the salt. Heat in a water-bath. Just before reaching the boiling-point the salt will melt and be absorbed by the earth. Allow it to remain about ten minutes in the bath—a little longer will not do it any harm (I find that taking it out of the bath and giving it a good boil assists materially)—then allow it to cool. When quite cool add a fragment of the crystal acetate of soda, when the whole will immediately crystallize. Let it do so thoroughly. Then add water in excess. Heat and empty into a large and suitable vessel, and add quantities of water to wash out the acetate. I find boiling water is the best, and that the process is much facilitated by the addition of a small quantity of hydrochloric acid. If necessary the process may be repeated. It may be as well to observe that in this, as in all the other washings, the great thing is plenty of water and plenty of patience. Working at it for an hour or two a day, you will be fortunate if you have got your diatoms thoroughly clean in a week.

Many works relate various methods of cleaning diatom earth, but the methods are somewhat intricate and the directions somewhat vague. It was not until Mr. Joseph Stevens, of 18, Conference Street, Christchurch, came on a visit to Oamaru and showed us his method that we were able to work satisfactorily. And I may say I have never seen better specimens of mounting than those given me by Mr. Stevens.

Mr. Stevens's method is first boiling the disintegrated earth with strong sulphuric acid—the strongest possible. After boiling a few minutes add cautiously small quantities of chlorate of potash while boiling. The quantity of H2SO4 used is about twice the quantity of earth to be acted on, which must contain as little moisture as is conveniently possible. The boiling is continued until the earth becomes either brown or pitch-black, which depends on the quantity of organic matter in it, and the consequent charring or carbonising of the organic dirt. The chlorate of potash is added while boiling, to bleach the earth. (Some authors recommend permanganate of potash as being safer.) The oxygen unites with the carbon, and in a short time the blackened earth is as white as snow. This process, which is conducted in a large test-tube, is the first step, and you will succeed better by not attempting to work with too much earth at a time—a teaspoonful, or even less, is quite enough. And I would caution you to be very careful when first bringing the sulphuric acid to, a boil. Do not be in a hurry—bring it by gentle degrees to a boiling-point; for sometimes it is jumpy, and will suddenly explode out of the test-tube, to the ruin of your table, clothes, and hands. This can be entirely obviated by patience. Remember also that the

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boiling-point of sulphuric acid is very high, so do not put your test-tube down in a cold place. The next step is to plunge the contents of your test-tube into a flask containing pure cold water. I use a Florence flask for this purpose, containing nearly a pint of water. Pour the boiling sulphuric acid and diatoms (safer to let it cool) into this flask. Do it carefully. It will make a noise, but will do no harm. Let your diatoms settle to the bottom, which they will do in a variable time according to their cleanliness and size (twenty minutes to two hours). You must wash them at least four times to get out the acid. The next step is boiling in an alkali. Here we must be careful and not employ too strong an alkali, neither must we boil it too long, or else your diatoms will disappear. It is true that Mr. Morland recommends boiling alternately in H2SO4 and strong liq. potassæ to get rid of refractory dirt in certain instances; but this is unnecessary here. The cheapest material to use is that recommended by Mr. Stevens, and that is “Hudson's extract of soap”—“washing-powder,” as used by our housewives for their clothes. We now proceed, using the Florence flask. Having washed out the acid, add a little hot water to the diatoms, and also about 10 or 20 grains of soap-extract—about as much as will cover half an inch of the large blade of your pocket-knife—and boil this—boil it till it boils freely, and stop. Let the diatoms settle. As it cools shake it occasionally to disentangle any diatoms that may be entangled in the scum, and fill the Florence flask up with pure hot water. Some of the débris, &c., removed by the soap-powder will rise to the top and some will be held in suspension by the water, the diatoms remaining at the bottom. You will now require three or four washings in pure water to get rid of your alkali, and you may now take a little up with a pipette and examine it under the microscope. You must not be disappointed if you find it still full of dirt, and sand, and débris. You may find one or two clean enough to pick off and mount, but there will not be many.

This is the whole process of cleaning so far as chemicals are concerned, and it must be repeated until under the microscope you see the diatoms are free from the minute grains of sand which spoil them. You will have to go through this process perhaps a dozen times before they are quite clean, but, having cleaned them, you will be well rewarded for your trouble.

One great difficulty is to get rid of the sand. Mr. Stevens's plan is to place the cleaned diatoms in a large circular flat-bottomed glass dish—a butter-dish or finger dessert-glass; then shake them up and rotate them as the digger does to separate his gold-dust. When rotating you will see the sand and large spicules collect in the centre at the bottom of the glass, while

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your diatoms are floating in the water and flying round and round; then with an ordinary glass syringe suck up the diatoms and squirt them into another glass ready for them, when they will fall to the bottom, and may be collected again clean and free from all coarse sand.

Mr. C. Peach, of Oamaru, has devised a better and more simple plan—one which has the advantage of not running the risk of breaking the valves. Mr. Peach's plan consists in getting a triangular glass dish, which he makes by procuring a triangular piece of glass 4in. to 6in. long and 2in. to 3in. or more broad at the base and ½in. at the apex. He cements to the sides and base narrow strips of glass, about ½in. broad, leaving the mouth open. He holds this dish so that the base is lowest, and puts in a small quantity of the cleaned diatoms and sand, then shakes it gently and taps the trough gently underneath and harder at the base. The sand goes to the lowest part, and the diatoms rise and separate, flowing towards the mouth in the direction given them by the tapping. When well separated it is a very simple matter to pour them into a clean test-tube, and then, when settled down, take up and mount either as a general slide or as a selection.

Here you must remember, unless you have got rid of all the acid and all the alkali you will have trouble: firstly, the diatoms will stick to the glass so that you cannot pick them off; secondly, they will not take kindly to your mounting-medium, and you will be vexed to find them full of air-bubbles.

However, we have now got our clean diatoms. Collect some of the clean sediment in a pipette, and let a drop fall on a perfectly clean slide. Unless the glass is clean the water will not run freely in all directions, and the diatoms will not be equally distributed. You may even find that with all your trouble there is still some sand left. Well, do not mind: this is easily got rid of. Just hold the slide nearly level in your left hand, and tap, tap with the middle-finger nail of the right hand, and you will soon see all the sand collect in a mass at one edge, while the diatoms are distributed evenly all over the slide. This is one of Mr. Stevens's choicest plans, and he deserves credit for its simplicity.

Now to pick them off. You can do this slowly while it is wet by chasing any specially large diatom to the edge with a bristle, then bringing it out of the water, letting it dry, and then picking it up; but I do not recommend this plan. It may be useful for beginners, but it is a waste of time.

The proper method is to proceed as follows: The diatoms being evenly distributed and the sand at one edge, heat the slide gently over a spirit-lamp to drive off the moisture and dry the diatoms. Put on one side to cool. Then, if you have not already prepared some slides, do so in the following manner:

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On the reverse side of the slide you are going to use describe a circle of ink, eitther with or without the turntable, in the centre of the glass. This ink-circle is to serve as a guide for you to place your diatoms. Dry it. Then, on the proper surface of the slide put a drop of very weak gum-water so as to cover the space occupied by the ink-circle on the other side. This gum-water must be very weak, and should be filtered; and must be fresh, or else it gets full of fungus.

I adopt a solution of arabin instead, to avoid the nuisance of having to freshly prepare the gum-water each time. The method of preparing arabin is given in the “Microtomists' Vade-mecum” (A. B. Lee). Arabin is the pure gum-extract of gum acacia or arabica, and is prepared by pouring a small quantity of thick gum-and-water into a large quantity of alcohol or spirits of wine. The arabin is insoluble in spirit, and separates as a thick, white, flocculent, opaque mass. It curdles the more as you add more spirit to it. It is then collected by filtering and drying; it is then washed in absolute alcohol and dried again: the result is a fine, pure white powder, freely soluble in water. I prepare it by adding a solution of corrosive sublimate to it, and make a strong solution, from which to make from time to time thinner solutions for use. Practice will quickly teach the proper strength. Well, having put a thin coat of arabin on the slide and dried it, we proceed to pick off our diatoms.

The best thing that I have found for this purpose is a cat's whisker fastened on a thin handle so as to leave about ⅓in. of whisker projecting. It is useful to have two or three of these, mounted with various thicknesses, for some diatoms come off easier with one than with the other.

Use a low power to examine your diatoms, and when you find one you want get it in the centre of the field and pick it up. With a little practice you will soon find that the diatom adheres very readily to the bristle or whisker. Now steadily transfer it to the centre of the dried gum. In the same way take off a few others. Now, if you wish you can arrange them in order in rows, or any design you please. Take the slide and breathe on it. This melts the gum or arabin, which runs into the diatoms. While the gum is wet you can push the diatom into any position you like, but it dries very rapidly, and then the least touch will break the diatom. If not satisfied breathe heavily again on the slide. By degrees you will arrange them as you please.

I have recommended mounting on the slide, but this is for beginners: it is much easier. Mounting on the cover-glass gives the best results, and should be the plan adopted.

However, next comes the mounting-medium. Diatoms may be mounted dry, or in some fluid medium such as Canada

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balsam. If mounted dry they must be mounted on the cover and placed in a cell. Mr. Morland contributed an excellent paper on mounting-media for diatoms to the “Journal of the Quekett Club,” August, 1887. And he remarks that diatoms mounted dry cannot be examined under immersion lenses. Another medium—a saturated solution of biniodide of mercury and iodide of potassium—owing to its high refractive index, 1·68, the highest known in any aqueous solution, gives beautiful results, but it is very questionable whether it will last. “The refractive index of this medium is represented by the number 25, as compared with 11 in Canada balsam. In other words, the image is nearly two and a half times as strong.”*

Mr. Morland, however, recommends Canada balsam as the best all-round medium. He also recommends styrax. I find this medium is generally coming into use amongst diatomists. It certainly shows up the finer diatoms and the fine markings much better than balsam. It is prepared by getting the ordinary styrax from the chemist, which, by the way, is not true styrax. True styrax has disappeared from commerce, and is replaced by “Liquidambar orientalis,” belonging to the order of the “Altingaceæ,” or else by “Liquidambar styraciflua,” from America. It is very dirty, and for use is prepared by dissolving it in pure benzole or chloroform, filtering, and then drying on a plate in a cool oven to the consistency of shellac, redissolving in benzole or chloroform, filtering twice, and then evaporating to the proper consistency. To avoid disappointment it is as well to remember that the chloroform or benzole must be pure. You will be vexed with the results given by ordinary benzole. “Jackson's” benzole is reliable and the only one to be depended on. It is, however, expensive and scarce.

A mixture of styrax and balsam has been recommended, but I have not tried it. Mr. Morland utterly condemns gum dammar. Other media have been recommended, but in the meantime I would advise Canada balsam or styrax, or a mixture of the two.

To mount the slide, warm it gently, and warm also the cover-glass: put a drop of balsam or styrax, enough for the purpose, over the diatoms, and apply the cover-glass: heat it gently, and examine to see if your specimens are free from air-bubbles; if not, heat to a greater degree, and while warm tap the slide as for the removal of sand, and you will see the air-bubbles come to the edge.

Specimens mounted in Canada balsam do not require a ring of cement, but specimens mounted in styrax must always

[Footnote] * “Microtomists' Vade-mecum.”

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be ringed. Any of the various cements described will do. I have, myself, used Judson's gold-paint or Kitton's cement, the formula for which is equal parts of red-lead, white-lead, and litharge ground together to a fine powder, and mixed when required for use with a little gold-size.

Description of Plates XVIII-XXIII.

Plate XVIII.—Map of Oamaru and district, showing the diatom outcrops or faces at Cormack's siding, Jackson's, Bain's, and Allen's farms. The dotted lines show the area of diatomaceous deposit as mapped out by Mr. Isdaile. Diatom earth has also been ploughed up in Cave Valley and on the east side of the Waiareka Creek. None has, however, yet been found on the west side of the creek, nor on the hills near Totara Round Hill. A small deposit occurs just where the road crosses the railway-bridge to Enfield, but it is of no importance, and is much mixed up with the calcareous débris of the disintegrated limestone.

Plate XIX. has been described in the letterpress. (See p. 295.)

Plate XX.—All these figures represent the diatoms of the different deposits, with their characteristic appearance, as shown under a power of about 75 diameters. To have been quite accurate, those in Jackson's and Bain's should have been shown rather larger.

Fig. 1. Deposit from Cormack's siding.

" 2. " H. Allen's farm.

" 3. " Totara estate.

" 4. " Jackson's farm.

" 5. " Bain's highest deposit.

" 6. Foraminifera from Jackson's and Bain's farms.

Plate XXI.—

Fig. 1. Triceratium venulosum, var. major, Gr. and St., n. sp.

" 2. " coscinoides, Gr. and St., n. sp.

3 3. " rugosum, Gr. and St., n. sp.

" 4. " dobreèanum, var. nova-zealandica, Gr. and St., n. sp.

" 5. Trinacria simulacrum, Gr. and St., n. sp.

" 6. Triceratium morlandii, Gr. and St., n. sp.

" 7. " oamaruense, Gr. and St., n. sp.

Plate XXII.—

Fig. 8. Triceratium crenulatum, forma gibbosa (?), Gr. and St., n. sp.

" 9. " " Gr. and St., n. sp.

" 10. Rutilaria radiata, Gr. and St., n. sp.

" 11. Actinoptychus vulgaris, Schum., var. maculata, Gr. and St., n. sp.

" 12. Auliscus oamaruensis, Gr. and St., n. sp.

" 13. Aulacodiscus janischii, Gr. and St., n. sp.

" 14. Eunotogramma weissei, Ehr., var. producta, Gr. and St. (Valve.)

" 15. Eunotogramma weissei, Ehr., var. producta, Gr. and St. (Frustule.)

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Plate XXIII.—

Fig. 16. Trinacria ventricosa, Gr. and St., n. sp. (Primary valve.)

" 17. " " " " (Secondary valve.)

" 18. Pseudo-rutilaria monile, Gr. and St., n. sp., n. gen.

" 19. Hemiaulus ornithocephalus (?), Grev., var. (?). (Frustule.)

[In this figure half of the adjoining valve is drawn, showing its beak-like claw or spine, by which the opposite valves are attached.]

" 20. Kittonia eláborata, Gr. and St., n. sp., n. gen.

" 21. Navicula margino-punctata, Gr. and St., n. sp.

" 22. Triceratium barbadense (?), Grev.

" 23. Aulacodiscus sollitianus, Norm., var. nova-zealandica, Gr. and St., n. var.

List of Diatoms found by Messrs. Grove and Sturt in the Diatomaceous Ooze from Cormack's Siding, Oamaru, and published in the “Quekett Journal” (alphabetically arranged).

Actinoptychus nitidus, Grun. (Heliopelta nitida, Grev.).

A. pulchellus, Grun., var. tenera.

A. simbirskianus, A. Schm.

A. splendens (Shadbolt), Ralfs.

A. (splendens, var.?) glabratus, Grun.

A. (glabratus, var.?) elegantulus, n. sp., Gr. and St.

A. undulatus, Ehr.

A. (undulatus, Ehr., var.?) constrictus, n. sp., Gr. and St.

A. vulgaris, Schum., var. maculata, n. var., Gr. and St.

A. wittianus, Janisch.

Amphipropra rugosa, Pet.

A. (?) cornuta, Chase.

Amphora cingulata, Cleve.

Amp. contracta, Grun. (var.?)

Amp. crassa, Greg.

Amp. furcata, Leud. Fort.

Amp. interlineata, n. sp., Gr. and St.

Amp. labuensis, Cleve.

Amp. obtusa, Greg.

Amp. (sp.?)

Amp. subpunctata, n. sp., Gr. and St.

Amp. tesselata, n. sp., Gr. and St.

Anaulus birostratus, Grun.

An. (?) subconstrictus, Gr. and St., n. sp.

Anthodiscus florèatus, n. sp., nov. genus, Gr. and St.

Arachnoidiscus ehrenbergii, Bail.

Arach. indicus, E.

Asterolampra decora, Grev.

Ast. marylandica, Ehr.

Ast. uraster, n. sp., Gr. and St.

– 306 –

Aulacodiscus amænus, Grev., var. sparso-radiata, n. var., Gr. and St.

Aulac. angulatus, Grev.

Aulac. barbadensis, Ralfs, “Pritch.”

Aulac. cellulosus, n. sp., Gr. and St.

Aulac. cellulosus, Gr. and St., var. plana.

Aulac. comterii, Arnott, var. oamaruensis, Gr. and St.

Aulac. convexus, n. sp., Gr. and St.

Aulac. crux, Ehr.

Aulac. elegans, n. sp., Gr. and St.

Aulac. huttonii, n. sp., Gr. and St.

Aulac. janischii, n. sp., Gr. and St.

Aulac. janischii, Gr. and St., var. abrupta.

Aulac. margaritaceus, Ralfs.

Aulac. margaritaceus, Ralfs, var. debyana, Gr. and St.

Aulac. margaritaceus, Ralfs, var. undosa, Gr. and St.

Aulac. radiosus, n. sp., Gr. and St.

Aulac. rattrayii, n. sp., Gr. and St.

Aulac. sollitianus, Norm., var. nova-zealandica, n. var., Gr. and St.

Aulac. spectabilis, Grev.

Auliscus barbadensis, Grev.

Aul. cælatus, Bail.

Aul. fenestratus, n. sp., Gr. and St.

Aul. grevillei, Jan.

Aul. hardmanianus, Grev.

Aul. inflatus, n. sp., Gr. and St.

Aul. lacunosus, n. sp., Gr. and St.

Aul. lineatus, n. sp., Gr. and St.

Aul. notatus, Grev.

Aul. oamaruensis, n. sp., Gr. and St.

Aul. propinquus, n. sp., Gr. and St.

Aul. pruinosus, Bail.

Aul. (pruinosus, var.?) confluens, Grun.

Aul. punctatus, Grev.

Aul. punctatus, Bail., var.

Aul. racemosus, Ralfs.

Biddulphia chinensis, Grev.

B. dissipata, n. sp., Gr. and St.

B. elegantula, Grev.

B. (?) fossa, n. sp., Gr. and St.

B. lata, n. sp., Gr. and St.

B. oamaruensis, n. sp., Gr. and St.

B. pedalis, n. sp., Gr. and St.

B. podagrosa, Grev., var.

B. punctata, Grev.

B. reticulata, Roper, forma trigona.

B. tenera, n. sp., Gr. and St.

Picture icon

To illustrate Paper by H. A. de Lautour.

Picture icon

To illustrate Paper by H. A. de Lautour.

Picture icon

To illustrate Paper by H. A. de Lautour.

– 307 –

B. tuomeyii, Bail.

B. vittata, n. sp., Gr. and St.

B. (Cerataulus ?) reversa, n. sp., Gr. and St.

Brightwellia pulchra, Grun.

Campyloneis (grevillei, var. ?) argus, Grun.

Cerataulus johnsonianus (Grev.), Cl.

Cer. marginatus, n. sp., Gr. and St.

Cer. polymorphus, Kütz., forma minor.

Cer. subangulatus, n. sp., Gr. and St.

Chætoceras gastridium (Ehr.), Grun., var.

Clavicula aspicephala, Paut.

Cocconeis barbadensis, Grev.

Coc. costatata, Greg.

Coc. naviculoides, Grev.

Coc. nodulifer, n. sp., Gr. and St.

Coc. pseudo-marginata, var. intermedia, Grun.

Coscinodiscus angulatus, Grev.

C. bulliens, A. Schm.

C. centralis, Greg.

C. concavus, Greg., nec Ehr.

C. curvatulus, Grun.

C. decrescens, Grun.

C. eccentricus, Ehr.

C. elegans, Grev.

C. elegans, Grev., var. spinifera, Gr. and St.

C. griseus, Grev., var. galopagensis, Grun.

C. inequalis, n. sp., Gr. and St.

C. kützingii, A. Schm.

C. marginatus, Ehr.

C. minor, Ehr.

C. nitidus, Greg.

C. oamaruensis, n. sp., Gr. and St.

C. oblongus, Grev.

C. oculus iridis, Ehr.

C. radiatus, Ehr.

C. radiosus, Grun.

C. rothii, Grun.

C. scintillans, Grev.

C. subtilis, Ehr.

C. subtilis, var. symbolophora, Grun.

Cosmiodiscus normanianus, Grev.

Craspedoporus elegans, n. sp., Gr. and St.

Dicladia capreolus, Ehr.

Dimeregramma fulvum (Greg.), Ralfs.

Donkinia antiqua, n. sp., Gr. and St.

Entogonia davyana, Grev.

Eunotogramma (?) bivittata, Grun. and Paut.

Eunotogramma weissei, Ehr., var. producta, n. var., Gr. and St.

– 308 –

Euodia janischii, Grun.

E. striata, n. sp., Gr. and St.

Gephyria incurvata, Arnott.

Glyphodesmis marginata, n. sp., Gr. and St.

Glyphodiscus scintillans, A. Schm.

Glypho. stellatus, Grev.

Goniothecium odontella, Ehr.

Grammatophora oceanica, Ehr.

Hemiaulus amplectans, n. sp., Gr. and St.

Hem. amplectans, var. major, n. sp., Gr. and St.

Hem. angustus, Grev.

Hem. barbadensis, Grun.

Hem. dissimilis, n. sp., Gr. and St.

Hem. includens (Ehr.), Grun.

Hem. lyriformis, Grev.

Hem. ornithocephalus, Grev.

Hem. polymorphus, Grun.

Hem. (?) tenuicornis, Grev.

Hyalodiscus arcticus, Grun.

Hyal. radiatus (O'Meara), Grun.

Hyal. subtilis, Bail.

Huttonia alternans, n. gen., n. sp., Gr. and St.

Hutt. virgata, n. gen., n. sp., Gr. and St.

Isthmia enervis, Ehr.

Kittonia elaborata, n. gen., n. sp., Gr. and St.

Kitt. virgata, n. gen., n. sp., Gr. and St.

Lampriscus (?) debyii, n. sp., Gr. and St.

Liradiscus ovalis, Grev.

Mastogloia reticulata, Grun.

Melosira borreri, W. S.

Mel. clavigera, Grun.

Mel. oamaruensis, n. sp., Gr. and St.

Mel. sol, (Ehr.), Kütz.

Mel. westii, W. S.

Nitzschia antiqua, n. sp., Gr. and St.

Nit. grundlerii, Grun.

Navicula apis, Ehr.

Nav. biconstricta, n. sp., Gr. and St.

Nav. braziliensis, Grun.

Nav. decora, n. sp., Gr. and St.

Nav. definita, n. sp., Gr. and St.

Nav. dispersa, n. sp., Gr. and St.

Nav. gemmata, Grev.

Nav. (Alloneis ?) grundlerii, Cleve and Grun.

Nav. inelegans, n. sp., Gr. and St.

Nav. interlineata, n. sp., Gr. and St.

Nav. margino-lineata, n. sp., Gr. and St.

Nav. margino-punctata, n. sp., Gr. and St.

– 309 –

Nav. placita, n. sp., Gr. and St.

Nav. prætexta, Ehr.

Nav. sandriana, Grun.

Nav. smithii, var. nitescens, Greg.

Nav. sparsipunctata, n. sp., Gr. and St.

Nav. spathifera, n. sp., Gr. and St.

Nav. trilineata, n. sp., Gr. and St.

Orthoneis splendida (Greg.), Grun.

Paralia sulcata (Ehr.), Cleve (Orthorisa marina, “S.B.D.”).

Plagiogramma (constrictum, var?) nancoorense, Grun.

Plag. neogradense, Pautocsek.

Plag. tesselatum, Grev.

Podosira hormoides (Mont.), Grun.

Pod. maxima, Kütz.

Porodiscus hirsutus, n. sp., Gr. and St.

Por. interruptus, n. sp., Gr. and St.

Pseudo-rutilaria monile, n. sub-gen., n. sp., Gr. and St.

Pyxidicula cruciata, Ehr.

Pyxilla dubia, Grun.

Pyx. johnsoniana, Grev.

Pyx. reticulata, n. sp., Gr. and St.

Pyx. (?) (Pterotheca, Kitt.) aculeifera, Grun.

Rutilaria epsilon, Grev.

Rut. epsilon, var. tenuis, n. sp., Gr. and St.

Rut. lanceolata, n. sp., Gr. and St.

Rut. radiata, n. sp., Gr. and St.

Stephanogonia danica (Kitt.), Grun., var.

Stephanopyxis barbadensis (Grev.), Grun.

St. ferox (Grev.), Grun.

St. grunnowii, n. sp., Gr. and St.

St. turris (Grev.), Grun.

St. turris, var. brevispina, Grun. (And numerous other forms belonging to Stephanopyxis.)

Stictodesmis australis, Grev.

Stictodiscus californicus, Grev., var. areolata, Grun.

Stict. californicus, var. nitida, n. var., Gr. and St.

Stict. hardmanianus, Grev., var. megapora, n. var., Gr. and St.

Stoschia (?) punctata, n. sp., Gr. and St.

Synedra crystallina (Ag.), Kütz.

Terpsinoe americana, Bail.

Terpsinoe americana, Bail., forma trigona, Pautoc.

Triceratium americanum, Ralfs.

T. americanum, var. quadrata, n. var., Gr. and St.

T. arcticum, Bright.

T. arcticum, var. permagnum, Janisch.

T. arcticum, Brightw., forma quinquelobata.

T. ausliscoides, n. sp., Gr. and St.

T. barbadense, Grev.

– 310 –

T. bimarginatum, n. sp., Gr. and St.

T. capitatum, Ralfs.

T. castellatum, West.

T. concinnum, Grev.

T. condecorum, Ehr.

T. cordiferum, n. sp., Gr. and St.

T. coscinoide, n. sp., Gr. and St.

T. coscinoide, var. quadrata, n. sp., Gr. and St.

T. crenulatum, n. sp., Gr. and St.

T. crenulatum, forma gibbosa, n. sp., Gr. and St.

T. denticulatum, Grev.

T. divisum, Grun.

T. dobreèanum, Grev., var. nov.-zealandica, n. var., Gr. and St.

T. eccentricum, n. sp., Gr. and St.

T. exornatum, Grev.

T. favus, Ehr.

T. favus, var. quadrata, Grun.

T. favus, (Ehr.), var. pentagona.

T. grande, Brightw.

T. grande (B.), forma quadrata.

T. harrisonianum, Norm. and Grev.

T. inelegans, Grev., var.

T. intermedium, n. sp., Gr. and St.

T. kinkerianum, Witt.

T. lineatum, Grev.

T. lineatum with two processes, Grev., var.

T. lobatum, Grev.

T. montereyii, Brightw.

T. morlandii, n. sp., Gr. and St.

T. neglectum, Grev.

T. nitescens, Grev.

T. oamaruense, n. sp., Gr. and St.

T. obesum, Grev.

T. papillatum, n. sp., Gr. and St.

T. parallelum (Ehr.), Grev., forma trigona, A. Schm.

T. parallelum, forma trigona, var. gibbosa, Gr. and St.

T. parallelum, forma quadrata = Amphitetras parallelum (Ehr.), Grev.

T. plumosum, Grev.

T. pseudo-nervatum, n. sp., Gr. and St.

T. rectangulare, n. sp., Gr. and St.

T. repletum, Grev.

T. rotundatum, Grev.

T. rugosum, n. sp., Gr. and St.

T. sexapartitum, n. sp., Gr. and St.

T. shadboltianum, Grev.

T. spinosum, Bail., var. ornata, n. var., Gr. and St.

T. stokesianum, Grev.

– 311 –

T. trisulcum, Bailey.

T. unguiculatum, Grev.

T. venosum, Bright.

T. venulosum, Grev., var. major, n. var., Gr. and St.

T. weissii, Grun.

T. weiseflogii, n. sp., Gr. and St.

T. parallelum (Ehr.), Grev., with seven angles, Gr. and St.

T. parallelum (Ehr.), var. gibbosa, forma ovalis, Gr. and St.

Trinacria ligulata (Grev.), Gr. and St.

Trin. pileolus, var. gutlandica, Grun.

Trin. simulacrum, n. sp., Gr. and St.

Trin. ventricosa, n. sp., Gr. and St.

Xanthiopyxis oblonga, Ehr.

X. constricta, Ehr.