On the elephant seal (Macrorhinus leoninus, Linn.) / by William H. Flower.

  • William Henry Flower
Date:
1881
Catalogue details

Licence: Public Domain Mark

Credit: On the elephant seal (Macrorhinus leoninus, Linn.) / by William H. Flower. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    lopment of the canine teeth, ns can he well seen in the figures of the type skull of the female M. angustirostris, as given by Allen. On comparing the upper surface of this with a series of male skulls, it will be seen that the difference consists chiefly in the extent to which the maxillae project beyond the sides of the praemaxillae, which in the former is almost nil, and in the latter very considerable, to allow room for the roots of the great canines on each side of the praemaxillae. Even in the youngest skulls this difference in the sexes is seen. The variations in the proportion of the breadth of the rostrum measured at the middle, halfway between the nasal orifices and the ends of the praemaxillae, in different specimens, are shown in the fol- lowing table:— Length of skull. Breadth of middle of rostrum. Proportion, length of skull being 100. Very young female, No. 3934, Mus. Roy. Coll. Surg mm. 204 mm. 46 22-5 The type specimen of M. angusti- rostris (according to Allen’s fig.), female 24-3 Very young male, No.3934 a, Mus. Roy. Coll. Surg 233 59 25-3 Adult male, No. 3920, Mus. Roy. Coll. Surg 437 144 33-0 Adult male, No. 3921, Mus. Roy. Coll. Surg 403 154 333 Adult male, No. 3921 a 564 176 31-2 There is certainly one character by which the type specimen of M. angustirostris, judging from Gill’s description and Allen’s figure, differs from any of the skulls of southern Elephant Seals with which I have compared it. This is the shorter antero-posterior extent of the palate-bones, and the deeper emargination of their hinder border. Before this distinction can be accepted as a specific character, it should be known whether it is constant. There is much variation in the size of the palate-bones of the southern forms : the length from before backwards between the palato-maxillary suture in the middle line and the spine in the large skull No. 3921 is but 35 millims. ; in the somewhat smaller skull. No. 3920, the same distance is as much as 51 millims.; and in the largest skull (No. 3921a) it is 65 millims., therefore about double that of the skull which comes nearest to it in general size. When the idea prevailed that each species was separately created in the region which it inhabits, geographical reasons were stronger than now for assigning specific distinction. But Allen fully admits, indeed suggests himself, that the two presumed species, though long isolated, have been derived from one stock, “the southern being an Proc. Zool. Soc.—1881, No. XI. 11 [17]
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