Art. VI.—On a (probably new) variety of the Small-nailed Seal,—Stenor Hyncus Leptonyx, of Cuvier, and De Blainville, and allied to the Phoca Leopardina, of Jameson.
(Read before the Philosophical Society of Canterbury, December 2, 1868.)
Early in the month of August, 1868, a Seal was caught in the harbour of Lyttelton, and afterwards was exhibited in Christchurch, which seemed to present some characteristics worthy of notice, and which, indeed, seems to differ from any of the varieties hitherto described.
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It measured over eleven feet eight inches in entire length, and six feet in girth at the stoutest part. From the decayed state of some of the teeth—the two under-canines being broken off near the gum, and one having a hole three-fourths of an inch deep—the animal must have been full-grown, and even aged. The upper canines projected fully an inch and a half from the level of the gum. Teeth, incisors, 4/4 canines, 1·1/1·1; molars, 5·5/5·5. The dentition, and the very marked tricuspid appearance of the molars, proved its identity with the genus Stenorhyncus.
There was no external ear. Bristles only on the upper lip. No soft, upstanding, furry hair, as in the Stenorhyncus Weddellii, or Sea Leopard, but only the thin, sparse, longish hairs, lying close to the skin, and distributed over the whole body. The swimming paws much resemble those of the Macrorhinus, or Sea Elephant, having more the shape of a fin, or wing, than of a paw. The nails are small upon the fore-paws, and very small, but still present, upon the hinder extremities. These last were scarcely, if at all, lobed, and more resembled fish-tails.
In colour, the animal was grey above, with black flakes, and a brownish tinge, all over the central part of the upper surface. On the sides, the black spots were replaced by white flakes; while the under part of the body was light grey. The fore-paws were white, with light grey flakes. The hinder extremities were black, with light grey spots.
There was no tail, nor even the rudiment of one. The vertebral column terminated, in a round compressed manner, under the skin, which extended about three inches beyond it, so as to form the curve which united the two hinder extremities.
The anal aperture was quite distinct from the urethro sexual canal, as if there were no common cloacal sphincter muscle; this appearance may, however, have been partly owing to the relaxed state of the animal's flesh, it having been dead for some time, and partly to the great pressure of the body upon the lower surface.
The weight of the animal was said, by the capturer and exhibitor, to be about 1,200lbs.; it was, probably, a little over half that figure.
I had an opportunity of afterwards examining a Sea Leopard (Stenorhyncus Weddellii), and comparing it with the above description. But this second individual exactly suited the ordinary account of the animal as I have named it. It possessed a covering of fur on the upper part of the body, and a tail about three inches long, and was decidedly smaller in size.
In attempting to define the place of the seal, described above, it may be sufficient to refer to the number and kind of the teeth. Of the eight genera, into which seals are now distributed, two possess the same number of teeth,—thirty two,—viz., Stenorhyncus and Pelagius, but the under molar teeth of the latter are not tricuspidated, and the upper molars are but slightly notched.
Confining our attention to the two species of the Stenorhyncus, the Leptonyx, or Small-nailed, and the Sea Leopard, we find the character of the former, which notes the presence of the small nails both in the hinder and
former extremities, decides the place of this animal. But when we take into account the colours of the flakes which spot its whole body, the very slight indentation of the lobes of the hinder extremities, and the entire absence of a tail, it seems as if it had claims to be regarded as an entirely new species.