56 EDWARD A. WILSON. 



than that between any two other digits, and the depth of the space between the first 

 and second is rather less than that between second and third or third and fourth. 

 The nails show no sign of wear and tear, but have the appearance of having grown in 

 water, though with transverse ridges indicative of periodic fluctuations in their growth. 

 That the limb in its functional use more closely approaches the type of limb found in 

 the Otariidse is most obvious when the living animal is observed, though in its general 

 shape and outline in the dead animal it is more like the fore limb of the Phocidse. 

 The fore limb is still functional as a support on land to a far greater degree than it is 

 in any member of the Stenorhinchinse. Hair covers the palmar surface of the fore 

 limbs to the extreme ends of the digits. 



The hind limb, on the other hand, has everything in common with the hind limb 

 of the more specialised of the Phocidse. In it only the merest traces of vestigial nails 

 can be discovered on the first and fifth digits, and no trace whatever of nails on the 

 second, third, or fourth. The first digit is in a remarkable degree larger and wider 

 than the fifth, though both are of a similar outline, the two limbs being well adapted 

 to form a powerful fin or rudder when used in conjunction, either palm to palm in a 

 vertical position, or outspread horizontally to form together an apparatus resembling the 

 fluke of a whale. The three central digits, webbed almost to their tips, are long and 

 tapering, but the third, which is the shortest, is about half as long as the first or fifth, 

 and the second is slightly longer than the fourth. 



That they are all well supplied with muscles which allow of adduction and 

 abduction can be seen in the living animal, not only when under water but when lying 

 on shore and in the act of stretching ; the hind limbs are thus often extended to their 

 widest limit when the free edge of the webbed limb, instead of being deeply concave 

 in outline as it is when at rest, becomes straight or even somewhat convex. 



Of facial bristles there are in the Antarctic specimen five rows on each side of 

 the muzzle, and the bristles themselves are black and twisted. There are also eight 

 conspicuous bristles in a clump over each eye. The hair is " flat, truncated, adpressed," 

 as described by Gray, and resembles most nearly in character the hair of Ommatophoca 

 and Cystophora. 



In examples so young as this male, the characteristic proboscis, as I have already 

 mentioned, is not yet fully developed, though three transverse creases in the skin of 

 the nose are distinct, and indicate its extensibility. The profile outline of the head in 

 such an animal when excited shows a more pointed physiognomy than would appear in 

 the profile of the same animal when at rest, this being due to the partial inflation 

 of the nasal sac ; the external nares being thus forced out, open forwards and 

 downwards, instead of upwards. 



There is, I think, room for doubt as to whether Macrorhinus is really, as it has 

 been considered, the most specialised form of the Phocidse. Macrorhinus in all its 

 movements is far more like one of the Otariidse than is any other member of the true 

 Phocidse. The fact cannot but be noticed by anyone who has watched both classes of 



