OF THE 



UNIVERSITY 



SEAL-KMBRYOS. 11 



terrestrial Carnivora as given by Drs. Parsons and Windle (14), to see what evidence, 

 if any, could be obtained in support of Mivart's suggestion that the Otaries may have 

 been derived from bear-like ancestors, while the Phocidse had another, possibly Lutrine 

 origin (8). 



From the fact that the muscles which show distinctive characters between the 

 Ursidse and the Mustelidse are with one exception (viz. the Rhomboideus profundus as 

 a separate muscle) confined to the limbs, the very positions in which adaptive 

 peculiarities would probably be most apparent, it might be inferred that but little 

 evidence would be forthcoming from this source. As a fact, however, the altered 

 position and functions of the limbs seem to have produced, at least in the embryo, 

 comparatively little change in the muscular attachments. 



Anterior extremity. (i.) The Supinator longus is a well-marked muscle inserted 

 into the lower end of the radius. It arises from high up on the shaft of the humerus 

 close to the tuberosities, there being practically no origin from the supra-condylar 

 ridge. The origin of the muscle agrees closely with that of Trichechus, but would 

 appear to correspond only with the second additional belly arising from the deltoid 

 ridge which Dr. Murie described in Otaria jubata. The attachments also further 

 correspond with those found in Lutra. According to Drs. Parsons and Windle this 

 muscle is constantly present in the Ursidse, Viverridse and in most of the Felidse, but 

 absent in the Canidse and Hysenidse. 



(ii.) The Pronator radii teres is inserted into quite the lower end of the radius, 

 and I could find no deep head of origin. This attachment agrees with what 

 Drs. Parsons and Windle found throughout the land Carnivores, and they point out 

 that the insertion is " of some interest from a systematic point of view." The insertion 

 found in the seal agrees with that found in the Ursidse and many Mustelidse, including 

 Lutra vulyaris. The description given by Dr. Murie in Otaria is rather ambiguous, 

 but the attachments would seem to be more extensive, though it must be remembered 

 that he is describing the conditions found in the adult animal, and it is quite possible 

 that in the seals the terrestrial condition found in the foetus may, when the limb 

 becomes functionally powerful, give place to more extensive bony attachments. 



(iii.) Flexor carpi radialis is inserted into the bases of the first and second 

 metacarpals, the latter attachment being the smaller, and has disappeared altogether 

 in Otaria. The insertion into both metacarpals agrees with the condition found by 

 Meckel in Ursus arctos. 



(iv.) Palmaris longus. The attachments of this muscle appear to vary considerably 

 in the land Carnivora. Drs. Parsons and Windle describe this muscle as composed 

 of external and internal portions, both of which are present in the Procyonidse alone, 

 the muscle being frequently absent altogether in the Ursidse. They find both portions 

 of the muscle present in Lutra cinerea, while in the majority of the Mustelidse, 

 including L. vulgaris, the large external one alone was present. Both portions are 

 present in the embryo seal, the external being the larger. The condition approximates 



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