100 Dissection of the Phoea cnstata. 



This hood is strongly muscular, with an aggregation of 

 circular fibres around its external orifices, which are two, 

 situated at the lower anterior part of the hood : these proba- 

 bly served the purpose of sphincters, so as perfectly to close the 

 sac. 



The length of the upper jaw beyond this crest, is chiefly 

 attributable to the ossa intermaxillaria, which are long and 

 broad. 



The entire number of teeth is thirty ; for an accurate ac- 

 count of which we refer to the preceding paper. 



The spine consists of twenty-nine pieces, viz. : five cervical, 

 fifteen dorsal, two sacral, and seven caudal vertebrae, which 

 were not complete, as a part of the tail had been cut off; 

 from report, however, there must have been as many as ten 

 caudal pieces. 



The ribs were fifteen in number, flat and slender. The 

 pelvis was long and narrow, having a direct diameter of only 

 three and a quarter inches, and resembling that of the otter. 

 Its cotyloid cavity inclined a little upwards, to which a strong 

 short femur is attached. Thyroid foramen small, and filled 

 with a dense ligament. 



The anterior and posterior swimming paws were exactly 

 similar in structure to the extremities of man ; having how- 

 ever a less number of metacarpal and metatarsal bones. 



In the anterior swimming paw, the phalanges decrease regu- 

 larly from the thumb to the little finger, whilst in the posterior, 

 the first and last fingers are longer than the intermediate ones 

 apparently, but not in reality, as this seeming increase is 

 dependent on an increased length of nail. The fingers are 

 not separate, but connected by a very thick web, the claws 

 appearing on its upper side and reaching to, but not over- 

 lapping the margin of the web. 



The diaphragm very strong and thick. 



The eye is very peculiar, perfectly spherical, with the nerve 

 entering directly in the axis of the ball. The sclerotica di- 



