The first sipunculid to be described was named Sipunculus œneus by Baird ^* in 1868. Eleven years later Captain Hutton ^† described two new species, which he named Sipunculus lutulentus and Phascolosoma annulatum. The former was obtained at Cape Campbell, at the north-east point of the South Island, the latter from Dunedin and Cape Campbell.

My attention was directed to the group by the gradual accumulation of specimens from various parts of the coasts of both Islands, and on dissecting a worm which agrees in external appearance with Captain Hutton's diagnosis of Phascolosoma annulatum I at once observed that it possesses internal characters that range it with quite a distinct genus—viz., Physcosoma (or Phymosoma, as it has been called up to within the last few years). This led me to examine those specimens in the store-room that retain labels in Captain Hutton's handwriting, with the result detailed below.

I find three such bottles or tubes, each containing a single specimen—namely, (a) labelled “Phascolosoma annulatum, Hutton, Dunedin”; (b) labelled merely “Cape Campbell,” containing a worm differing entirely from the preceding; (c) with a label the writing on which is almost obliterated, but which appears to be “Sipunculus cyaneus,” without any indication of locality. This specimen appears to have dried up at some time: it is hard, shrivelled, nearly black, and quite unrecognisable. I failed, unfortunately, to find any trace of tube or bottle bearing a label “Sipunculus lutulentus,” either in the store or in the Museum itself. It is possible that it was sent, together with a collection of annelids, to the British Museum by the late Professor Parker. The tubes (a) and (b) are either Hutton's “types” or “cotypes.” The worm contained in the former (a) is not Phascolosoma at all, but is Physcosoma, characterized by the crescentic form of the tentacular crown situated above the mouth, and by the longitudinal muscles being in several distinct bundles; that in (b) belongs to the interesting genus Dendrostoma, as is shown by the form and arrangement of the circumoral tentacular crown.

Physcosoma, Selenka, 1897 (=Phymosoma, auctorum).

Physeosoma annulatum, Hutton = (Phascolosoma annulatum, Hutton.)

As the specimen in the tube agrees almost precisely with Hutton's diagnosis I insert it here. In the original diagnosis, however, there are one or two slight errors, due probably to the examination of specimens imperfectly extended.

These I have corrected, and the corrections are indicated by italics:—

“Body papillose, cylindrical, tapers posteriorly; pale-brown, tubercles darker. Proboscis nearly as long as the body, and tapering gradually into it; posteriorly papillose, and coloured like the body; anteriorly smooth, very pale, frequently with some brown blotches; the anterior end encircled by about 18 to 20 narrow brown raised rings of hooklets. Mouth with a dorsal crescent of about 20 short blunt oral tentacles.”

Localities.— I have received specimens of this worm from the following localities, and in considerable numbers from some of these localities, viz.:—Stewart Island: Collected by the late Professor Parker, by Messrs. H. Suter, W. M. Thomson, and E. Jennings. Foveaux Strait: From the oyster-beds, collected by Mr. A. Hamilton. Warrington: Collected by myself. Dunedin: Collected by Captain Hutton. Specimens from each lot have been dissected, as well as the “cotype.” They all agrce in essential characters, of which a detailed account follows:—

Form of Body:— For descriptive purposes it is convenient to distinguish the body from the proboscis (or introvert), for the latter may be retracted within the former, unless the animal be carefully anæsthetised.

(a.) The body is, as usual, cylindrical, and pointed more or less markedly at its posterior end. It is widest in the middle, and somewhat tapered towards the base of the introvert. Usually the body is curved to one side, so that the ventral surface is concave. But if a series of specimens be studied this form is departed from in various degrees, owing partly to the different methods of preservation and partly to the different states of contraction of circular and longitudinal muscles at death. Now, as in times past stress has been laid on the form of the body in diagnosing species, it is worth noting one or two of the forms assumed owing to the above cause: The hinder moiety may be more strongly contracted than the anterior moiety, so that the posterior end looks somewhat like a tail; or the circular muscles at both ends may be more strongly contracted than those of the greater part of the body, and a more or less spherical form results; while at other times the middle of the body is constricted (See figures.)

(b.) The cylindrical proboscis, or introvert, when fully extended is much narrower, and usually as long as or even longer, than the body; but necessarily the proportions vary somewhat according to the condition at death.

The tentacles are twenty in number, short, finger-shaped, and grooved along their outer—i.e., oral—margin. They are arranged in the manner typical of the genus in a crescent

immediately above the mouth, with the concavity directed dorsally. In this dorsal gap are 4 black eye-spots; and occupying the intra-tentacular area is a somewhat rectangular disc, slightly lobed right and left to form 2 small rounded projections, which are only visible on extreme extension. As in some other species, such as P. varians, there is a post-oral collar, but it is very small in the present species.

Immediately below the mouth there are several circles of closely set hooklets, each circle having the appearance of a brown narrow ring. The number of these rings varies a good deal: Hutton gives 12 as the number, but in some I count 16 or 18, while in others, when mounted for microscopical examination, there are as many as 20—to which must be added some 5 or more very closely set rings at the oral end of the series, which are not recognisable except under a high-magnifying lens. The individual hooklets are much curved, as shown in the figure.

Colour:— The colour is highly variable; it is generally pale to dark brown, gradually becoming darker at each end. In some of the very pale specimens there are large blotches of very dark pigment, irregular in size and arrangement; but the ground-colour is always very pale—indeed, it appears white in preserved material—and the brown colour is due to pigment in the dermal papillæ which cover the body.

These papillæ are largest and most densely packed at either end, slightly larger—at any rate, in some individuals— at the anterior than at the posterior end, but along the entire ventral surface they are small; and both dorsally and laterally in the middle region of the body they are also quite small. These smaller papillæ have less pigment in them than the larger, so that this middle region is of a paler tint, for the papillæ are here more widely separated from one another, and allow a greater amount of ground-colour to come into view. The papillæ are of the usual circular form.

The anus is, generally, quite inconspicuous, but in some specimens it forms a slight prominence; and occasionally it appears as a paler spot in the dark-brown surroundings.

The colour of the introvert is usually paler than that of the body—sometimes, indeed, it is almost white—and in these cases it is often marked with dark-brown blotches, which are larger near the oral extremity. But the colour at the proximal region graduates into that of the body, and except in this portion, where the papillæ graduate into those of the anterior end of the body, the papillæ are quite minute and invisible without a lens.

Dimensions:— There is a considerable range in the size of the body of my specimens—from 20 mm. to 40 mm:—though an average specimen is about 30 mm. to 35 mm. The “type”

a lobule and 5 on the outer; thus there are about 160 to 176 tentacles altogether. Bach tentacle is grooved on its upper—i.e., oral—face. These grooves lead into a furrow running down the lobule; the latter leads to a similar furrow on the lobe; thence a furrow passes across the oral disc to the subcentral mouth, which is transversely disposed. The structure of this tentacular crown appears to relegate the worm to the genus Dendrostoma as denned by Selenka^* and by Shipley, ^† and the internal anatomy agrees with this diagnosis.

Colour.—The colour of the preserved specimens is a very pale yellowish-brown, and has a shiny appearance. The posterior end in some individuals is more definitely brown, while in other cases there is a well-marked dark ring round the base of the introvert. Some individuals are nearly white. Fortunately, I have a note as to the colour and appearance of the living worms collected at Warrington. They are white and smooth to the naked eye. Some are slightly brownish. One individual has white tentacles; in another these are reddish-brown; and Dr. Agnes Kelly, who collected a number of specimens at Waiheke, has noted that they are “yellowishgrey”; and in alcohol they have a more decidedly yellow tint than those collected by me.

The surface of the body is almost smooth in the preserved specimens; but posteriorly there are longitudinal and circular furrows which mark out irregular rectangular areas. These are distinctly visible in some individuals over the hinder third of the body, becoming more distinct as the extremity is approached. These rugosities appear again towards the base of the introvert. In Hutton's specimen (b), and in some individuals variously preserved, these furrows are much less evident than in others, so that the body appears in these cases much smoother and more shiny. Thus, in the Warrington specimens a hand-lens is required in order to see these very shallow circular furrows, whereas in some well-preserved individuals from Rangitoto and from Auckland they are very much more distinct, and the “raised areas” render the body rough-looking, especially posteriorly.

There appear to be no papillæ, but under a hand-lens minute black dots are recognisable sparsely scattered over the body, which are probably minute papillæ.

The introvert itself is smooth, paler in colour than the body, and is provided with 3 or 4 irregular circles of widely spaced blunt hooks, which are nearer together on the dorsal than on the ventral side. These circles of hooks occupy about the middle third of the introvert, the anterior margin of which is deeply pigmented, and forms a prominent collar.

Or, taking the proportional breadths and lengths, we have—

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I am not aware how far the proportional lengths of body and proboscis are of value in determining specific characters, but, seeing that in Physcosoma annulatum there is considerable variation in relative length of introvert and body, depending on the method of killing and so forth (see above), it is probable that the differences above tabulated may be explicable in the same way.

It will be noted that in the Auckland specimen the introvert is relatively nearly thrice as long as in the Cape Campbell specimen, and the question suggests itself, Was the introvert in the latter fully extended? No mention is made of the tentacular crown by Captain Hutton, and it is possible that the introvert was only partially everted. But the animal is relatively about one-third the diameter of the carefully killed individual from Auckland, which might be the result of killing it in strong alcohol.

We have, at any rate, I think, only a difference of size to contend with; and, failing other known differences, it is scarcely likely that this would be a specific difference, as amongst my material the individuals (some twenty or thirty) from Waiheke are much smaller than the Auckland or Warrington individuals.

As I have said, I can find no trace of the undoubted “type” of Sipunculus lutulentus, and in communicating with Captain Hutton on the subject he says that, as far as he remembers, he had only one specimen of S. lutulentus. If that is so, then the individual (b) must be the type, and Dendrostoma huttoni be replaced by D. lutulentum of the Index F.N.Z.

But now let us turn to Baird's description of Sipunculus œneus and compare it with Hutton's description of S. lutulentus, and I think we shall find that these two are synonymous. For ready comparison I will arrange the characters in parallel columns: first, Hutton's diagnosis of his species; secondly, Hutton's translation^* of Baird's Latin diagnosis; and, thirdly, Baird's longer description, which is here dissected.

It will be noted that the most striking difference in regard to the dimensions of these two species is exhibited by the “breadth of body anteriorly,” for in Baird's example this is very much less than in Hutton's. But, presumably, each took the greatest diameter, which in the former case is near the hinder and in the latter near the anterior end, and this greatest diameter is nearly identical. May we explain this difference in form by difference of contraction on death?

A comparison of the brief diagnosis of Sipunculus œneus with that of S. lutulentus presents only three apparent differences, apart from colour and dimensions—viz., the character of the surface of the body in the various regions: (a) the condition of the hinder end of the body; (b) the condition of the proboscis; and (c) the character of the skin of the body. In both the first two cases S. lutulentus is “rougher” than S. œneus. But if we read Baird's longer description we find that the “smoothness” referred to in the Latin diagnosis is qualified: the caudal extremity being “almost smooth,” and the proboscis “smooth-looking.” Now, as I have mentioned in the description of the species, I find a good deal of difference exhibited by the surface of the body of the specimens in my possession, depending on the mode of preservation. For example, in two of the Warrington individuals (killed slowly in alcohol) the reticulation—i.e., “roughness”—on the hinder end is by no means evident, and one would call it “smooth”; also, in most of the individuals collected in Auckland Harbour, at Waiheke (preserved in formol), the body appears smooth, whereas in others the body-wall is more strongly contracted and the reticulations are more prominent, (c.) Baird's species is said to be covered with “small warty-looking tubercles,” or, in the words of the diagnosis, the surface is, in the middle part of the body, “minutely granulated”; whereas S. lutulentus, according to Captain Ilutton, has a “smooth” body. In the account given of the specimens described in this paper I have mentioned the minute tubercles, and I find that in some individuals these are much less evident than in others, and no doubt this is due to the method of preservation.

As regards the colour, Baird's is “white,” Hutton's is “pale-brown.” Here, too, I find the same differences, as I have mentioned.

In conclusion, I believe that these two species are synonymous; and, notwithstanding the great difference in size-between these on the one hand and the numerous individuals in my possession on the other, I believe that the latter too are of the same species, which must stand as Dendrostoma œneum, Baird.