ABT. 15 ANATOMY OF THE EARED AND EARLESS SEALS HOWELL 107 



ences of insertion outnumber the resemblances. The muscles above 

 listed, both in origin and insertion, differ from those of the cat in 

 about 14 per cent more instances in Zalophus than in the Phoca^ but 

 the differences in origin are more numerous than those of insertion. 

 On the other hand, when these muscles of Zalophus are compared 

 Avith those of the Phoca it is found that the origins are more con- 

 servative, while the insertions are more prone to differ. 



Little or no account can be taken of muscles which may be rela- 

 tively more or less robust because of the difficulty of comparing the 

 cat, the lean otariid, and the fat phocid. The following comparisons 

 may, however, be made, with the cat as standard : 



Muscle conspicuously Irroader at oHgiu: Pectoralis in both, and 

 biceps femoris in Zalophus. 



Body muscles that are shorter: In both genera the sternomastoid 

 and scalenus, the latter in Phoca especially. 



Occipital rmtscles with hroader attachment : Cephalohumeral in 

 Zalophus. 



Occipital m,uscles with narroicer attachment: Cephalohumeral and 

 splenius in Phoca; biventer cervicis in Zalophus; and sternomastoid 

 in both, especially the Phoca. 



LiTnh muscles whose origins have shifted distad: Triceps medialip, 

 palmaris longus, flexores carpi ulnaris and hallucis longus, and ex- 

 tensor digitorum longus pedis in both animals. 



Limb muscles whose origins luive shifted proximad: Brachialis, 

 triceps longus, flexor digitorum longus pedis, and peronei longus and 

 brevis, in both animals. 



Lhnb muscljes whose insertions have shifted distad : Pectoralis 

 (part), humerotrapezius (especially in Zalophus), teres major, tri- 

 ceps longus, semimembranosus, semitendinosus, and biceps femoris, 

 in both ; deltoid, triceps lateralis, quadratus femoris, and adductores 

 I, 2, 3, and 5 in Zalophus; and atlantsocapularis inferior, psoas 

 magnus, iliacus, and gracilis in the Phoca. 



The inclusion or ommission of some muscles in the above groupings 

 are at times largely arbitrary, for it may be difficult to be sure whether 

 a muscle is attached only to the tibial head, for instance, or whether 

 it also encroaches upon the femoral condyle. Also it must be taken 

 into account that most of the limb muscles are relatively shorter 

 than those of the cat usually merely for the reason that the bones 

 themselves are shorter. 



It is to be seen that only two of the body muscles of the Pinni- 

 pedia listed in the tables (pp. 101 to 106) have become shorter, and 

 these to a very slight extent. One muscle of the occipital crest has 

 become broader and four others of this region narrower in their 

 attachment. The origins of five limb muscles have shifted distad 

 and five others proximad, to a very slight extent in all cases save 



