28 



BULLETIN OF THE 



In consequence of this peculiar They also (imperfectly) serve the 



structure the only purpose which purpose of walking; these animals 



these organs can subserve is that of being able to progress when out of 



swimming. On land progression is the water several miles an hour, and 



mainly accomplished by a wriggling to run for a short distance with nearly 



serpentine motion of the body, slight- the rapidity of a man.* 

 ly assisted by the extremities. 



In the Phocidce the tarsal articula- In the Otariadce the foot when 



tion allows but a small amount of similarly at rest forms with the leg 



movement of the foot, which when an angle of at least 90°. 

 naturally at rest forms but a slight 

 angle with the leg. 



In the Phocidce no unusual sexual In the Otariadce (in Callorliinus and 



difference in the form of the pelvis is Eumetopias^ at least) there is an 



known to exist ; the principal differ- exceedingly great sexual variation in 



ence being that the pubic bones are the form of the pelvis. In the males 



united for a shorter distance in the it is narrow throughout, and seen from 



females than in the males. In the the front the sides are nearly paral- 



Phoca vitulina the pelvis, seen from lei for the greater part of its length, 



the front, presents a pyramidal out- the pubic bones abruptly converging 



line, with the apex pointing back- posteriorly, and the ilia diverging 



ward. Laterally and ventrally its moderately at their anterior ends, 



outlines are straight. The front outline is gently hollowed. 



The ilia are short and broad The ilia are elongated (twice as 



(length and breadth about equal), ex- long as broad), flattened posteriorly, 



panding anteriorly in a transverse with their dorsal and ventral borders 



line. Their crests are turned abrupt- parallel, and no lateral expansion or 



ly outward and recurved, their pos- recurvation of the crest, 

 terior surfaces being concave. 



The pubic bones are straight, slen- The pubic bones are stout and sub- 

 der, and subcylindrical ; posteriorly cylindrical, a little broader and thin- 

 they become flattened and somewhat ner behind, approximating both an- 

 expanded dorso-ventrally. In the teriorly and posteriorly. Barelymeefc- 

 male they are appressed posteriorly ing (in the males) at the latter point, 

 for one third their length, their point they form with each other a more or 

 of widest divergence being at their less broad ellipse, which is only slight- 

 anterior ends. In the females, how- ly open anteriorly in Callorkinus, but 

 ever, they merely meet at the end, more widely in Eumetopias. They 



* See Captain Rryant's account, given below, of the habits of Callorkinus ursinus. 



t The pelvis of Callorliinus differs from that of Eumetopias somewhat in certain de- 

 tails of its structure, as will be shown later in the comparison of these two species under 

 C. ursinus. 



