240 EUMETOPIAS STELLERI STELLER's SEA LION. . 



B. TEETH OF THE LOWER JAW. 



SKELETON. Vertebral formula : Cervical vertebrae, 7: dorsal,. 

 15 5 lumbar, 5; caudal (including the four sacral), variable - 7 

 probable average, 16. 



Ten of the fifteen ribs articulate with the sternum 5 their 

 sternal portions are entirely cartilaginous. Their osseous por- 

 tions evidently increase much in length after middle age. The 

 apophyses of the vertebrae are well developed. Of the neural 

 spines of the dorsal vertebra?, the first, second, and third are 

 sub-equal, 130 mm. long; they gradually shorten posteriorly, the 

 last having a length of only 75 mm. 



The sternum is normally composed of nine thick and broad 

 osseous segments, the first and last very long, the eighth short- 

 est. Between the eighth and ninth a shorter cartilaginous 

 one is sometimes intercalated (as in specimen No. 2920). 



The pelvis is well developed. The ilia are very long and nar- 

 row antero-posteriorly. The pubic bones are unauchylosed, 

 they being merely approximate at their posterior extremities. 

 Probably in the females (as in Callorhinus ursinus), they are 

 widely separated, and the whole pelvis is much smaller than in 

 the males and differently shaped. 



The humerus, as in the other Pinnipeds, is short and thick, 

 with the greater tuberosity enormously developed. The bones of 

 the forearm are also very large and strong, with all their pro- 

 cesses greatly developed ; in length they but slightly exceed the 

 humerus. The length of neither of the segments of the arm 

 quite equals the length of the bones of the first digit (including 

 its metacarpal bone) of the hand. The first digit of the hand is 

 the longest, twice as long as the fifth, and very thick and strong. 



* The distance from the crown to the alveolus. 

 t The portion inserted in the jaw. 

 t At the base of the crown. 



