114 PEOCEEDLNGS OF THE NATIONAL MUSEUM vol. 73 



sented craniad, while the rear limbs play a very minor part as far 

 as I have observed, never being used in rhythmic motions, but in 

 various steering movements. During brisk swimming the forefeet 

 of the Phocidae are folded against the body save Avhen the animal 

 wishes to make a sharp turn, at which time the outside flipper will 

 be abducted and thrust against the water, as a man would push 

 against a wall in making a similar movement. When a seal is merely 

 loafing about in the water, with slight turns, rolls and such idle 

 actions without definite idea of progression, the hind limbs may be 

 entirely immobile while the forefeet maintain an intermittent " fid- 

 dling " movement, such as a man would employ while treading 

 water. I have no doubt that when the seal is suddenly alarmed 

 it employs its forelimbs in active swimming movements in any way 

 which might be of assistance in starting quickly. 



It is almost impossible to determine the degree of pronation and 

 supination of which the whole arm is capable, for so much of it is 

 within the body covering that in the entire animal one can not follow 

 the interaction of the joints, and after sufficient of the muscles have 

 been cut away to determine this the results are worthless because 

 many of the inhibitions to movement normally raised by taut mUvS- 

 cles and bulk of tissue have been removed. It is probable, however, 

 that at least in ZalopJais there is less of such movement possible 

 than in man, while in both there is more than in such a fissiped as 

 the cat. 



Few conclusions regarding the scapula may be reached, and its 

 chief stimulus for specialization in the Pinnipedia is doubtless as a 

 scaffold upon which are hung the arm muscles, rather than as an 

 attachment for muscles of the thorax and neck. It is relatively 

 moie robust in the Zalofhus^ as one would expect, but contrary to 

 expectations, the axillary border is relatively the longer in the Phoca; 

 for this animal has less need for a long lever arm for the triceps. 

 In the Otariidae at least the scapula is unusually mobile, and slides 

 about beneath the sidn when the animal is in terrestrial movement 

 in exaggerated manner. When resting with head low the scapulae 

 may be in contact, projecting for several centimeters above the dorsal 

 line, or by means of the serratus magnus and depressor scapulae 

 muscles the}' may be forced well ventrad, which correspondingly 

 lifts the body. Incidentally it may be mentioned that in most of 

 the articulated skeletons which one sees the thorax is elevated above 

 the ground to an unnatural extent. 



In the Zalophus the supraspinatus is large and powerful as an 

 aid to extension of the humerus but in the Phoca ^ it is considerably 

 weaker, as one would also expect. In both animals the infraspinatus 



'At least in Mirounga, among the Phocidae, the supraspinous fosi^a is relatively quite as 

 large as in the Otariidae. 



