ART. 15 ANATOMY OF THE EARED AND EARLESS SEALS HOWELL / O 



the dorsal border of the scapiUa onl}'. His long head corresponds 

 to the lower division of the long head in Zalofhus and upper division 

 of the lateral head in my Phoca. His external head corresponds to 

 my lateral head in Zalophus and lower division of the lateral head in 

 Phoca. And his internal head corresponds to my medial one. Murie 

 listed four similar divisions for Eumetopias and Odobenus. 

 Humphry reported that in Phoca the long head reached the paddle, 

 which has not been confirmed by anyone since. 



M. anconeus externus (figs. 9, 10, 20, 21). It is only because Murie 

 and Miller listed this as a muscle separate from the medial triceps 

 that I follow the same course, for in both my specimens the two were 

 fused. In both genera it may be said to originate from the lateral 

 epicondyloid ridge, with insertion along the dorsal two-thirds of the 

 external border of the olecranon. 



M. anconeus internus (figs. 9, 10, 22, 23) has origin from the same 

 situation in both Zalophus and Phoca — the entepicondylar ridge — 

 save that in the former it was from the most prominent part of the 

 bone, and in the latter, caudad of the entepicondylar foramen, rather 

 than from the more prominent part craniad thereto. Insertion of 

 both was upon the tuberosity upon the medio-dorsal part of the 

 olecranon. 



MUSCLES OP THE FOREARM 



The flexors consist of the following muscles : 



M. palmaris longus (figs. 10, 20, 22, 23) was of phenomenal power in 

 the Zalophus and was fused with the flexor carpi ulnaris. The two 

 together arose from the entire medial surface of the broad proximal 

 half of the ulna, including the olecranon. Certain of the more su- 

 perficial fibers decussated with those of the border of the triceps 

 longus. It rapidly became broadly tendinous (25 mm. wide) as it 

 passed over the wrist, was attached (the flexor ulnaris portion) to 

 the pisiform, and then spread as in Figure 22, a powerful branch 

 going to digit 1, and a weaker to digit 5, deep to its flexor sul)limis 

 tendon. It is j^erhaps the strongest flexor of the manus, working 

 upon the two borders in an extraordinarily powerful cupping action. 

 In the Phoca it was rather small and arose from the olecranon be- 

 tween the long abductor of the fifth digit and the internal anconeus. 

 Its tendon expanded to cover the three medial digits and adjoining 

 part of the carpus. 



It is difficult to see why Murie and Miller both made the mistake 

 they did in their treatment of this muscle. For Arctocephalus, Eurrie- 

 fopioj^^ and Ohohenus, the palmaris longus of Miller and primus of 

 Murie was really a superficial division of the digitorum profundus, 

 tentatively termed by me a flexor pollicis longus because of its posi- 

 tion. Innervation is by the median nerve, and although this fact 



