648 



3965. The upper and lower jaws, with the teeth, of an Ursine Seal, nearly allied to 

 the Arctocephalux lobatus, but with the canines of the lower jaw of a smaller 

 relative size. 



The outer walls of the alveoli of the canines and molars on the right side of both jaws have 

 been removed, showing that the four posterior upper molars are implanted each by two con- 

 nate fangs. In the posterior inferior molar the two fangs become quite distinct. 



Presented by Dr. Hobson. 

 Genus Otaria. 



Dental formula : t|=f, <?{=}, m j-^=36. 



3966. The skull of the Leonine Seal, Byron's ' Sea-Lion ' (Otaria jubata). 



This is the skull of the original specimen an old male brought from Tinian Island, by 

 Commodore Byron, in 1769, which was for many years preserved in the British Museum. 

 The superoccipital is broader and more nearly vertical than in the preceding specimens : the 

 basioccipital is carinate below ; the paroccipitals form an obtuse angle, but are less prominent 

 than the mastoids. The petrosals and tympanics are not expanded into a bulla ossea, but 

 send down a subcompressed smooth tuberosity. The pterygoids are pierced by the ectocaro- 

 tids. The bony palate is very long, and remarkably concave, from the bending down of 

 its sides : its posterior border is transversely truncate. The sagittal and occipital cristse are 

 singularly elevated. Each frontal sends out an obtuse process near its junction with the 

 parietal, into the middle of the extensive temporal fossa, and each developes large, horizontal, 

 triangular, postorbital processes. The maxillaries develope antorbital processes. The nasals 

 are short and broad, and articulate with the premaxillaries as well as the maxillaries. Most 

 of the teeth have been lost from this old skull : the sockets show the simple fangs of the 

 small molars : the outer incisors resemble small canines. 



Mm. Brit. 



3967. The skull of a male Leonine Seal (Otaria jubata). 



The hyoidean arch remains naturally articulated to it, the stylohyals being attached by 

 ligament to the outer side of the petrosals. The dental series is entire in the upper jaw, with 

 the exception of the left incisor, * 1 . The enamelled crowns of the molars are of very small 

 size, subcompressed, conical, with a cingulum round the inner side of the base, rising into a 

 rudimental cusp at its termination. The swollen fangs, with the thick covering of cement, 

 project from the sockets, and are divided by a constriction from the crown. The ectocarotid 

 canals are present, and the superorbital plates, but the processes from the posterior margin of 

 the frontals are not developed from this skull. 



Presented by Admiral Beaufort, C.B., F.B.S. 



3968. The skull of a female Leonine Seal (Otaria jubata). 



It differs from that of the male in its inferior size, but agrees with it in all the essential or 

 non-modifiable characters. The more feeble bite and smaller temporal muscles have not 



