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

  • Flower, William Henry, 1831-1899.
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.

    10/18 (page 154)
    Milk-Dentition.—As is well-known, in the Seals generally the milk-teeth are extremely rudimentary in size and form, and per- fectly functionless. They mostly never cut the gums, and are actually absorbed before birth. In a specimen of P/ioca vitulina, which was born in the Society’s Gardens in 1868, and which survived its birth exactly one week, the only traces of milk-teeth remaining were small rudiments of the upper canine and one molar on one side only. All the permanent teeth were in a nearly equal state of developmentl. The same condition has been observed in all the other species which have been examined. In Cystophora cristata, the nearest ally of the Elephant Seal, the milk-teeth, as observed by Reinhardt, are still more rudimentary2. On the other hand, in the Eared Seals (Otariidcz), which more nearly approach the terrestrial Carnivora in many points in their structure as well as habits, the milk teeth are better developed and less evanescent than in the true Seals, the canines especially being of moderate size and retained for several weeks. In the youngest skulls of the Elephant Seal which I have been able to examine, and which, from their size and general development, must be little more than new-born, the whole of the permanent teeth are fully in place, except the great canines, of which the apices only are appearing above the alveoli ; and I am not aware of any observations upon the milk-teeth of these animals, except one, which I was fortunate enough to make some years ago3, and which, from its extremely interesting nature, may be worth repeating here, especially as I am enabled to exhibit the specimen to the Society for comparison with the huge skull and teeth of the adult animal (see figs. Ia and 2a, pp. 150, 151). A foetal Seal is preserved in the stores of the Museum of the Royal College of Surgeons, only 11 inches (28 millims.) long from nose to end of hind feet, whence obtained I am not able to say, but which presents all the external characteristics of the species under consideration, and which, it should be mentioned, is of the female sex. It has no hair, except the whiskers and tufts over the eyes. The five short conical nails are all developed upon the fore feet. On the hind feet the position of all the nails is indicated by extremely minute depressed dots in the skin a little distance Irorn the end of the skin of the toe; in the three middle toes, which are of nearly equal length, these dots are scarcely 2 millims. from the extremity. In the two outer, longer toes they are about 9 millims. from the end, and more conspicuous than the inner ones. I mention these because it is often stated that there are not even rudiments of claws on the hind feet of the Elephant Seals. The jaws contained a set of very minute calcified teeth, viz. f, c. m. |-, on each side, being the complete number of milk-teeth which the species would have ; for the incisors and canines should 1 See W. H. Flower, “Notes on the First or Milk-Dentition of the Mam- malia,” Trans. Odontological Society, vol. iii. 1871, p. 211. 2 “ Om Klapmydsen’s uiodte Unge og dens Melketaadsset,” Naturbist. Vidensk. Meddelelser for 1*864. 3 See ‘ Journal of Anatomy and Physiology,’ vol. iii. 1869, p. 270.