Art. XV.—Further Notes and Observations on the Gestation, Birth, and Young of a Lizard, a Species of Naultinus.
[Read before the Hawke's Bay Philosophical Institute, 9th August, 1886.]
In a former paper, read here before you in the session of 1879, I gave some “Notes and observations on the animal economy and habits of one of our New Zealand Lizards, supposed to be a new species of Naultinus;” sectthat paper also contained an
[Footnote] § “Trans. N.Z. Inst.,” vol. xii., p. 251, etc.
account of some young lizards (4), that were brought forth in my house, two of which I succeeded in rearing. At that time, however, I knew nothing of the manner of their being brought forth or expelled by their parent (as I have pretty fully related in that paper); and now, having very recently gleaned a few more particulars respecting the same, which may prove both interesting and curious, and perhaps unique, I propose to bring the same before you in this paper.
Early in this year, 1886, I received from Mr. J. Stewart, of Takapau (a member of this Society), a fine specimen of our green lizard, in good condition and very lively. I suspected at the time it was a female, and probably pregnant. Mr. Stewart informed me that it had been very recently captured—viz., on the 29th December, 1885. It was some time, however, before I could get it to eat, although I supplied it with flies, much as I did my former ones. In time it ate them, but sparingly; and although I often watched it, I never once detected it doing so, or seeking to capture them! in this respect so very different to those I formerly had. Yet it ate them, that was certain, without leaving a wing or a leg, for they were not to be found in its house (or glass case), out of which they could not possibly get; and the fæces of the reptile further proved it. It also differed widely from my former ones in not drinking; for, although I often tried to induce it to drink, it never once took any water, while the others were frequently lapping water, and licking wet spots on leaves, etc.; and I did not keep any water with this lizard in its house. It would, however, swim very well and strongly when I put it into a large basin of water. As the weather became colder in this present autumn—in May—it ceased taking any flies, and I had supposed it was about to hibernate, as the others did; so I set it aside, but kept looking at it occasionally. The last time that I did so, on the 8th of June, it seemed much as usual, only thinner from its long fasting, and not torpid, but rather lively. I therefore gave it a couple of flies, which, however, it would not eat. On my looking at it again on the following day, the 9th of June, I found that it had given birth to two young ones—curious-looking little things and fully formed, but both dead. The following is a description of them:—
They were both nearly alike, in size, shape, appearance, colour and weight; each one distinct, lying separate in the case, and closely enwrapped in its own proper semi-transparent chorion or secundine, which was entire around one, and slightly broken about the snout of the other below its eyes, so that the front part of its little head appeared. Each was closely doubled up—one with its tail coiled tightly around its snout, and the other with its tail bent round and downwards beneath its chin; their shape was broadly oblong, one end much rounded, and
the other (containing the head) more produced; measuring, the one 8, and the other 9 lines in length, and 5 lines in width, compressed, with the surfaces smooth and flattened, but somewhat uneven owing to the prominencés of the limbs, etc., and bearing a general resemblance to the smaller seed of the common garden bean (Faba vulgaris). Each fetus weighed 15 grains, their colour darkish-green on the back, shaded off in spots to lighter green and almost to white in some of the little knobs and slight hollows; the eyes bright and yellow, with dark pupils, as in the adult. The chorion, or enveloping membrane, was excessively thin and white, and filled with minute capillary branching flexuous veins of a bright florid red colour, a few of the main ones being tolerably large, presenting a pleasing appearance. The fetus that had its enwrapment broken at its snout, had its mouth slightly open, showing the little notch in the tip of its tongue. From their very fresh, damp, and glistening appearance, they appeared to have been very recently expelled.
From these circumstances here related, three facts in the history of these little animals seem to be established:—1. That their young are brought forth alive, and not within an egg (as is the case with many of the Saurians); this I had formerly supposed (loc. cit., p. 264); 2. That their time of gestation must be at least 5 ½ months; 3. That they bring forth two at a birth—this, also, I had before observed (l.c., pp. 251 and 264).
A brief description of this adult lizard may also be here given, seeing it varies a little from the species described. Extreme length 6 ½ inches, of which the tail is 3 ½ inches; colour a uniform bright green above, (which is particularly vivid on casting its old skin or epidermis), inclining to darkish-green as it grows older, and much paler beneath; head rather small, slightly concave between the eyes, and scales flattish; tongue darkish plum-coloured; two large blunt semi-transverse scales on the side of the base of the tail near the vent, and three similar ones on the opposite side; a patch of pre-anal pores singly on larger scales in 4–5 short rows; toes slender, long; tail cylindrical, very slender, much elongated, its scales not imbricated.
In some of its characters this lizard resembles N. grayii, Bell,* especially in the shape of its head with flattened scales, the few large convex scales near the base of the tail, (which, however, in that species are said to be “four on each side,”) elongated toes, and uniform green colour. It has, also, a few characters in common with the species described by me—N. pentagonalis (loc. cit.)—as in its pre-anal scales with pores, elongated toes, and the colour of its tongue; still it seems different in other characters, and has certainly shown widely
[Footnote] * “Trans. N.Z. Inst.,” vol. iii., pp. 7 and 8.
different habits. It agrees still less with the other described species of green Naultini. It may be a variety of N. grayii, Bell, but certainly not of N. punctatus, Gray, which species Professor Hutton has subsequently stated to be identical with N. grayii.*
Addendum.—Since writing the above, and very recently, I have received a letter from Mr. D. P. Balfour, of Glenross, a member of this Society, dated 16th July, 1886, informing me of a green lizard, a species of Naultinus, and believed by him to be of the same species as N. pentagonalis, Col., which he had in confinement, having produced two young ones on the 14th of July. One of them was born alive, and the other dead, and then only after some considerable difficulty, Mr. Balfour largely assisting the mother; for when he saw her on this occasion, this second young one was half expelled, tail foremost, the other having been first born. Mr. Balfour also says that the living one measured 3 inches at its birth.
This is the third known instance of the birth of these green lizards, and all of them happened about mid-winter,† (a strange season !) when they should be in their natural semi-torpid hibernating state. This additional circumstance, now confirmed, seems very peculiar, and is worthy of being noted. The living young lizard, mentioned by Mr Balfour, seems to be of an extraordinary large size, “3 inches long when born:” those four born here with me, in 1878, were only a little over 1 inch in length when first seen, (loc. cit., p. 263), and those described in this paper (although still uncoiled in their fetal membranes), cannot be much more.
[Footnote] * “Trans. N.Z. Inst.,” vol. iv., p. 171.
[Footnote] †. See “Trans. N.Z. Inst.,” vol. xii., p. 251, for the first.