158 NOTES ON THE ANATOMY OF A SEAL — SOMMERS. 



an phalangeal bones are developed out of proportion to the 

 bones of the forearm, taken together they have a much greater 

 length, the flexors and extensors of the wrist, &c, are short and 

 thick, the tendons are long and well developed. 



The inferior extremities of the seal are also confined in the 

 general integument, the boues being shortened and otherwise 

 modified as in the anterior extremities, yet every bone is present 

 as in man, the gluteal muscles are short and well developed, but 

 it is evident from dissection that the other muscles of the hind 

 limbs in the seal are not so well developed as the corresponding 

 organs in the anterior members, the articulation of the femoral 

 bones, and the insertion of their muscles ar^ such that the infer- 

 ior extremities are twisted so that the tibial bones are external 

 to the fibulae, owing to this the palmar surfaces of the feet 

 become opposed to each other in a position similar to that 

 which can be produced in the hands of man by the partial rota- 

 tion of the radius upon the ulna. 



The phalangeal bones of the feet are longer than those of the 

 forelimb, the claws are not so large, the tegumentary covering, 

 broader and looser, allowing great freedom of movement in these 

 parts which are readily observed to be specially adapted for pro- 

 gression in the water, while comparatively useless for the same 

 purpose on land. The tibiae and fibulae were free. 



Opening the thorax, the viscera were examined ; larynx and 

 trachea same as in other animals, the rings of the latter being 

 however, complete ; right lung, upper lobe distinct ; middle and 

 lower imperfectly divided or marked off from each other ; left 

 lung distinctly two-lobed ; weight of lungs and heart, 1| lbs.; 

 heart large, notched at the apex, denoting imperfectly the septum 

 between the ventricles, four-chambered; the foramen ovale open* 

 Eustachian valve not more marked than in the heart of adult 

 human subjects ; ductus arteriosus not present. The aorta gave 

 off separate subclavian and carotid arteries for either side. The 

 anatomy of the vascular system in other respects differs not from 

 that of man. 



Of the abdominal viscera, the stomach was large, having the 

 bagpipe shape of the organ in carnivora, being also simple ; it 



