Maiuinalia. 13 



Quite as distinct in their own way are the teeth of the Gydo- 

 plwrinae. In these there is a simple conical crown, very feeble for 

 the size of the animal and wanting all trace of cusps on its cutting 

 edge. The root is swollen and bulbous. Somewhat similar, but 

 much stronger, are again the teeth of Halichmrus, and these in their 

 massiveness remind us of those of Monaclius. 



In the whole economy of the Antarctic Fhocidae, nothing can be 

 more remarkable than tlie divergences in the shape and size of the 

 cheek-teeth. Side by side, on the South Polar pack-ice occur four 

 genera, Lohodon, Ogmorhinus, Ommatoiohoca, and Leptonychotes. 

 Living the same life, with the same sources of food around them, 

 and, moreover, with the same number of teeth, no two genera agree 

 in any single respect in the form and pattern of the individual 

 grinders. In Ogmorliinus there is found the most formidable, in 

 Ommatophoca the most feeble, dentition of the family. Again, while 

 Lohodon seems to find necessary for its existence a set of teeth 

 surmounted by perliaps the most complicated arrangement of cusps 

 found in any living mammal, Lep)tonyc1iotcs survives on the same 

 ice-floe with the help of a simple fairly strong dentition. Lastly, 

 while there is, so far as is known, little individual variation in 

 the three remaining genera, in Ommatophoca there occurs one of the 

 most remarkable instances of individual variation in mammalian 

 teeth known to science. Not only are the size and the number of 

 the roots of each tooth variable, but the actual number of teeth in 

 any particular specimen can never be foretold with certainty. 



Nothing can be more certain than that such a state of things 

 as I have here described cannot be meaningless. Developments like 

 these must in each case be connected with habits and food, which 

 must surely differ in a manner corresponding to such remarkable 

 differences of structure. This supposition is, I think, supported 

 by the fact that, as already stated, there are to be found amongst 

 the Antarctic PJiocidae resemljlances of dentition to those of northern 

 seas. Thus it is reasonable to suspect that the resemblances between 

 the teeth of Ogmorhinus and of Phoca hispida are not altogether 

 without reference to similar uses. 



With a view to approach the root of this matter I have examined 

 with some care all the available accounts of the habits of the 

 Antarctic Fhocidae. Meagre as these are, they are sufficient to 

 afford me some assistance, especially those of Dr. Racovitza. 

 Thus the fact that Ogmorhinus is alone described as occasionally 

 killing and eating Penguins, and that one of these Seals accepted as 

 food the bodies of two of these birds thrown overboard from the 



