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Show 490 DR. ST. G. MIVART ON THE PINNIPEDIA. [May 19, addition to this, however, there is a faint trace of a frontal postorbital process. The anterior nares do not extend far backwards. The palate is prolonged backwards behind the last molars, and its hinder margin is slightly concave. The palatine foramina open on its hinder half. There is hardly any true paroccipital process, but, as in the last-noticed genus, a vertical ridge near it projects backwards and away from the bulla. The mastoid is prominent, and its prominence is continuous with that of the squamosal above the external auditory meatus, immediately above which opening is a great antero-posteriorly extending bony swollen prominence. The meatus opens between the outwardly projecting mastoid and the postglenoid process, so that practically its lateral walls, but not its floor, are prolonged outwards. There is a chink-like postglenoid foramen. The basis cranii is always level, but slightly convex antero-posteriorly. The mandible has no subangular process, but in the place where it should be the bone is rounded. The coronoid is pointed, but small and low, hardly rising above the condyle. The maxilla develops a preorbital process. The symphysis is not prolonged. Dentition:-I. % C. \, P. * M . \=32. The molars are very small, and have pointed, recurved crowns, mostly with a marked posterior accessory cusp and sometimes with one in front also. Monachus 1.-This genus, of one species from the Mediterranean and Black Seas and the Atlantic Ocean about Madeira and the Canary Isles, resembles the three preceding genera in having the nails of the hind feet rudimentary, and the first and fifth toes greatly longer than the others. The nails on the fore feet are also rudimentary in this genus. There are 15 dorsal, 5 lumbar, 2 sacral, and 11 caudal vertebrae. The skull in its main characters resembles that of Phoca, The crista galli-and cerebellar fossa of the petrosal are rather larger. The condyloid foramen is distinct, and placed midway between the condyle and the foramen lacerum posterius. There is a distinct preorbital process on the front rim of the orbit and developed from the maxilla. The nasals are not anchylosed together, and the premaxillae ascend to meet them. The palate is concave behind, and its concave border is medianly notched. I have observed no defects of ossification in the basi- or exoccipitals, but (as in P. barbata) a venous channel traverses the supraoccipital opening by transverse apertures above the foramen magnum and inside its margin. There is a very large aperture on either side of the basis cranii bounded by 1 Phoca monachus, Hermann, Beschaf't. d. Berlin. Gesell. natur. Freunde, iv. 1779, p. 456, pi. 12, 13. Phoque a ventre blanc, Buffon, Hist. Nat. Supp. vi. pi. 44; Cuvier, Oss. Foss. Atlas, vol. ii. pi. 218. Monachus mcditerrancus, Nilsson, Kong. Vet.-Akad. Handl. Stockholm (1837), p. 235. Leptonyx monachus, Schreber's Fortg. Wagner, vii. p. 40. Monachus albiventer, Gray, Cat, Seals Brit. Mus. (1866) p. 17- Allen N. Amer. Pinnipeds, p. 465. |