78 PROCEEDINGS OP THE NATIONAL MUSEUM vol.73 



to those of man, but there seems to be some doubt as to whether they 

 are homologous. 



In the Phoca the flexor digitorum communis arose by three heads. 

 Caput a had origin from the medial epi condyle below the flexor 

 carpi radialis ; caput h had origin from the whole of the medial sur- 

 face of the olecranon and from two-thirds of the shaft of the ulna ; 

 while caput c originated from the radius, upon the ulnar side of the 

 pronator teres insertion. The three heads joined to form a very 

 broad tendinous band which split into five branches, one going to 

 each digit. This was substantially the same as conditions in the 

 Phoca vituUim of Miller, who called caput a the flexor sublimis, 

 caput J) the flexor profundus, and caput c a flexor pollicis longus. 

 His nomenclature may possibly be correct and the divisions seem to 

 be homologous with those of Arctocephalus^ but they certainly are 

 not with those bearing the same terms for Ewmetopias, as designated 

 by Murie. 



M. flexor carpi radialis (figs. 9, 22, 23) lay upon the ulnar side of the 

 pronator teres. It arose in both animals from the medial epicon- 

 dyle. In the Zaiophus its tendon inserted chiefly upon metacarpus 

 one deep to that of the supinator longus, but a tenuous branch went 

 also to metacarpus 2. In the Phoca insertion was also upon meta- 

 carpus 1 and 2, and probably 3 as well. Miller reported three 

 branches to the three metacarpals in Phoca and three in Arclocep/ta- 

 lus to the first two metacarpals and the ligament between the trape- 

 zium and trapezoid. In Eumietopias insertion was upon the first 

 metacarpal only. 



M. pronator quadratus (fig. 9). Murie found this muscle in Odohenus 

 but not in Eumetop'ws^ while Miller did not find it at all in Phoca or 

 Arctocephalus. In the Zaiophus it was represented by a few fibers 

 upon the flexor side of the interosseous membrane, while in the Phoca 

 it was weaklj' though indubitably present. 



M. Hexor carpi ulnaris (figs. 10, 21, 22, 23) in the Zaiophus was fused 

 with the palmaris longus. It was the ulnaris portion of the latter 

 muscle, however, that was attached to the pisiform. In the Phoca it 

 was located between and deep to the palmaris and long abductor of 

 digit 0, and was a robust muscle. Origin was from the medial 

 olecranol border, with a rather complex insertion, for although there 

 was attachment to the pisiform as usual, the main thread of the 

 tendon continued to metacarpus 5. In addition a tendinous fascia 

 was given off mediad, this forming a second and deeper palmar fascia, 

 and this curved deep and laterad to form part of the thick sheath of 

 the flexor digitorum communis. In Arctocephalus and Eumetopias 

 it was very similar to that of Zaiophus. In his Phoca Miller reported 

 the same condition found by me in the same genus, save that he made 



