OCR Text |
Show 488 DR. ST. G. MIVART ON THE PINNIPEDIA. [May 19, It is noteworthy that the mastoid process is not so large relatively in certain old individuals as in younger ones. The palate has a concave hinder margin. The anterior nares are very high. Dentition :-1.1, C. \, P. j, M . [=34. Molars large, conical and simple, generally without accessory cusps. Their apices are slightly recurved, and the anterior and posterior edge of each is rather sharp. All have but a single root, save the true molars and the fourth upper premolar. It is only these three teeth which ever have accessory cusps. Stenorhynckus l.-This genus consists of two species, confined to the Antarctic and Southern oceans. The hind feet are almost or quite clawless, and the first and fifth toes greatly exceed the others in length. There are 14 or 15 dorsal, 6 or 5 lumbar, 3 sacral, and 12 or 14 caudal vertebrae. The skull presents the characters already enumerated as occurring in Phoca, except that the premaxillae do not attain, or hardly attain, the nasals, which are more or less completely anchylosed together. There may be hut very small defects of ossification in the occipital. The long descending process of the parietal hardly attains the alisphenoid. The cerebellar fossa of the petrosal is small. There is a moderate paroccipital process. The optic foramina may (they do in S. leptonyx) unite inwards to open into the cranial cavity by a single and median aperture. The hamular processes of the pterygoids may be long, as in S. carcinophagus, or hardly any, as in S. leptonyx. The bulla may not be so prominent as in Phoca. The glenoid foramen is in the form of a small fissure, placed rather on the inner side of the postglenoid process. There is a large preorbital process on the maxilla, a structure which is only represented by a rudiment in Phoca and Halichcerus, so far as I have seen2. The palate is strongly notched behind medianly. There is no subangular process to the mandible, and the angle may be almost obsolete, though marked in S. carcinophagus, while the coronoid process is lower than in Phoca and Halichcerus. Dentition:-I. | C. \, P. {, M . \. The molars (which are, except the first, two-rooted) may, as in S. leptonyx, have three pointed cusps well separated, the middle being the largest and slightly recurved towards the apex, the apices of the other two being inclined towards the long cusp, or else, as in S. carcinophagus, they may have subcompressed, much elongated crowns with a principal recurved cusp with a small one in front of it, and one, two, or three accessory cusps behind it, the principal cusp being somewhat bulbous at the apex. 1 Gray, Voy. of Erebus & Terror, Mam. i. p. 2, pis. 1 & 2; Cat. Brit. Mus. p. 15 ; De Blainville, Osteographie; Schreber, Fortg. Wagner, vii. pp. 36-38; Cuvier, Oss. Foss. Atlas, vol. ii. pi. 219. fig. 2. This is the Ogmorhinus of Peters, Monatsbr. K. P. Akad. Wissen. Berlin, J 875, p. 393, note;' Allen, N. Am. Pinniped, p. 466. It is also the Lobodon of Gray, Voy. of Erebus & Terror, and Catalog. Brit. Mus. p. 8, and of Allen, N. Amer. Pinnipeds, p. 466. 2 A rudiment of this process is also found in Lutra and Ursus, but in no other land Carnivora, so far as I have observed. |