218 THE ANTARCTIC MANUAL. 
and in other regions its food supply is derived from creatures which 
need some holding, yet which are not so strong or active as those 
which serve to nourish Ogmorhinus. The external shape of Leptony- 
chotes is that of an animal fitted for rapid motion in the water, so 
that it is natural to suppose that fish may form no small portion of 
its diet. 
Lastly, we have Ommatophoca, with its very feeble and variable 
dentition, yet comparatively strong lambdoid crest. It is evident that 
the exact number of its teeth is not of importance to this animal. 
Even their size is sufficiently variable to admit the thought that the 
whole dentition is little used. It seems to me highly probable that 
Ommatophoca is in the process of losing its teeth. Its food is soft, 
consisting, according to Monsieur Racovitza, of large cephalopods. 
Such crushing of these as may be necessary would be performed as 
well by the flat jaws as by cusped teeth like those of the Phocide. 
Consequently the teeth are in a state of degeneration. But inasmuch 
as the large size of the cephalopods entails some munching, since they 
could hardly be swallowed whole, as might be the Luphausia, the 
muscles which move the jaws are necessarily stronger than in Lobodon 
or Leptonychotes, as shown by the fairly strongly developed lamdoid 
crest. This supposition agrees very well with that which I have 
already brought forward in the case of Lobodon. In the case of Lobo- 
don the teeth are highly developed, not for grinding purposes, but for 
use as a sieve. In Ommatophoca, not being available as a sieve, they 
are useless. They thus fall outside the influence of Natural Selec- 
tion, except in so far as their reduction may be of use to the species. 
Variation and enfeeblement results, a process which, if for the advan- 
tage of the animal, will no doubt be carried to its full extent. My 
supposition is supported by the external appearance of the animal as 
graphically described, I think for the first time, by Monsieur Raco- 
vitza. It is, he writes, “Le plus phoque des phoques, car chez lui 
toute forme de quadrupéde a disparu. Son corps n’est plus qu’un 
sac fusiforme pourvu de membres trés réduits,” from which I gather 
that Ross’ Seal does not possess the natural appearance which 
belongs to an agile carnivore such as Ogmorhinus.* 
LEPTONYCHOTES WEDDELLI. 
External Appearance.—This species seems to be recognisable rather 
by its negative than its positive characters. Although spotted, it 1s 
not so distinctly or abundantly so as the True Sea Leopard, so that 
* See also Mr. Borchgrevink’s description of his supposed new species of Seal under 
Ommatophoca, p. 223. 
