Mammalia. 63 



teeth, as is actually the case, would not 1)6 so strong as those of the 

 original series. Yet it is necessary to consider the matter, especially 

 in view of what has already been written concerning it. 



And first it is advisable to consider what is the normal cheek- 

 dentition of Ommatophoca. As long as only two skulls were known, 

 I think there could be no doubt that it was necessary to regard it as 



4x4 1x1 

 (following the analogy of other Seals) p.m. j^ m. . This 



view was certainly not shaken by the arrival of the two specimens 

 brought home by the ' Belgica' since this dental formula was then 

 represented on both sides of two skulls and on one side of a third, as 



against only one skull with a complete dentition of pm. and m. . 



Now, however, that the ' Southern Cross ' specimens are added to the 

 series, we may divide the skulls before us into the following 

 classes : — 



(I.) Those with p.m. ^— ^ m. ^^ (nos. 43.11.25.4 and) ., 

 4x41x1 f- 



700). ) 



(II.) One with practically the same dentition, but with an extra\ 



tooth, apparently as a 'daughter' of p.m. — on the left! , 



side and the remaining premolars apparently in a state I 

 of semi-reduplication (no. 3246.) 



(III.) Those with ii.m. and m. „ — in each case at first) 



5x5 (4 



sight by reduplication of m. - (nos. 700,4,3 and 2). I 



— a result in the face of which it clearly behoves us to reconsider our 

 opinions as to what must be properly regarded as the normal dentition 

 of Oriimato'pliom. 



In view of the probable capture in the near future of further 

 examples of this most interesting Seal, it is not safe to venture on 

 positive assertions as to the intricacies of its dentition. It is 

 impossible, however, to avoid the suspicion that the four skulls of 

 Class III. are those of individuals in which a normal complement of 

 two upper molars is in process of reduction, that those of Class I. 

 are skulls of individuals in which such a reduction has taken place, 

 and that No. 3246 is an altogether abnormal and unusual variation — 

 an example, in fact, of quite a different class of variation. 



Coupled with the feebleness of dentition, which I have already 

 pointed out, nothing could be more natural than reduction of the 

 teeth. This is, as is so well shown in the short-jawed races of the 

 human species, first manifested by a lessening in size of the last 



