76 PKOCEEDIXGS OF THE ISTATIONAL MUSEUM vor,. 73 



was inferentially mentioned by Miller, he did not take into account 

 that such innervation prevents affinity with the palmaris. There 

 was intimate attachment of its tendon to the palmar fascia, indubi- 

 tably, and ultimately the fusion Avill probably be complete, but care- 

 ful dissection proves that the main portion of the tendon extends 

 to the pollex. Miller's palmaris superficialis and Murie's secnndus 

 division were merely the antibrachial extension of the pectoralis, 

 which also had intimate connection with the palmar fascia. I found 

 nothino^ whatever in the Phoca that could correspond with JVIiller's 

 second head of the j^almaris for the same genus. His first head is 

 very similar to the muscle as I found it. 



iW. pronator teres (figs. 9, 10, 22, 23) lay mediad of the biceps and 

 brachialis. In the Zalophus it arose in intimate relation with the 

 flexor carpi radialis from the proximo-caudal margin of the medial 

 epicondyle of the humerus. In the Phoca it was from practically 

 the same spot. Insertion in both wiis upon the radius from near the 

 bicipital rugosity to just distad of the process or angle near the 

 center of its radial border. 



The ulnaris and radialis muscles of the Mammalia are usually 

 rather uniform in their locations, but the digitorura muscles — espe- 

 cially the flexors — are annoyingly in the habit of occurring in a great 

 number of combinations. In many cases these are of such a nature 

 that it is unwise to place too much reliance upon the homology as 

 indicated by the nomenclature employed, for in this case the innerva- 

 tion proves to be of little or no aid. Not only does origin vary, but 

 the tendons of insertion are often unreliable as criteria for nomen- 

 clature — a muscle homologous with a pollicis may not reach the 

 thumb, or a digiti quinti the fifth digit. The pinnipeds have these 

 flexor muscles of such a sort, and I deem it eminently wise not to 

 refer to the muscular divisions by name but by number, for they are 

 not now to be homologized with any certainty. 



M. flexor digitorum communis (figs. 9, 10, 22, 23) in the Zalophus 

 consisted of four separable elements, while in the Phoca there were 

 three which were separable only at origin. 



Caput 1 (figs. 10, 22) in the Zalophus was a part of Murie's flexor 

 sublimis digitorum in Eu/nietoplas. It arose upon the ulna from 

 caudo-mediad of the sigmoid cavity, passed distad directly super- 

 ficial to the second division and split into three branches which went 

 to the three lateral digits. The one to the third proved to be double, 

 however, and there seemed to be a broadening of the tendon in the 

 direction of digit 2, possibly indicating the relic of a former branch 

 at thifS point. These three tendons were the most superficial of any 

 going to their respective digits, the one to the fifth ultimately passing 

 superficial even to the lateral palmaris longus branch. (See fig. 22.) 



