62 Soiitlic)')i Cross, 



(li'srrilHtl— an iiistain-"' in wliiili, of ciijlit known examples, only two 

 rw<enil>k' catli otIuT. 



The first ju-obleni then which eunfronts us is tlie explanation of 

 such varialiilily. It can be no more meaningless than is, as a rule, 

 the ri'inarkal>ly delinite form and condition of Mammalian dentition. 

 The une^tion is — can we ])ossibly find the meaning ? 



To mv mind there is one point wliidi stands out most clearly in 

 ruiiartl to a case like the present. The animal whose teeth are 

 subject lo such variation can have no use for a stable dentition. 

 Just as the highly specialised complications of the crowns of the 

 cheek-teeth of Lohodon must have arisen through some very special 

 nee«l of the animal — some very specialised manner of feeding for 

 which the i)articular form of tooth must bean advantage — so it seems 

 clear that (hainatopkoca must be an animal, the capture and ingestion 

 of whose food is not aft'ected by changes in its dentition. I go 

 further e\"en than this, since I believe that, as already explained, the 

 animal is in the course of losing its teeth. The dentition shows a 

 condition of extreme weakness. The teeth are small and feeble, and 

 it is to this very feebleness that I feel inclined to attribute the 

 variability as regards the roots. It seems to me, in fact, as if the 

 strength to form a completely double-rooted tooth is frequently 



absent. I would suggest then that except for ]xm. — and ^ the 



doul'le -rooted tooth must be the normal, the single-rooted a variation. 

 My sui)positiou gains strength from the fact that in all the eight 

 skulls there is no instance of a double-rooted first premolar — a 

 variation which should assuredly, one would tlunk, occur, were 

 variations towanls. strength and not towards weakness the rule. 

 Taking the renuiining cheek-teeth of the left side, of sixty teeth 

 41» or over 8U per cent, are more or less double-toothed, while of the 

 remainder many are small, imperfectly formed, or mere "daughter" 

 toeih of one of the supi)osed cases of reduplications. It seems 

 impu.s8ible to doul)t then that, following the analogy of other Seals, 

 the i^jsterior cheek-teeth of Oinmatopkuca aie normally double- 

 r«x)led. 



Liistly comes the (piestiou of the supposed redui)lication of teeth, 

 a iK>int upon whicli I have, in the earlier part of this article, followed 

 the nomenclature and suggestions of previous writers. Viewed in 

 the light .if my jirevious suggestion.s, the possibility of reduplication 

 or the reverse loses much of its importance, since it is probable that, 

 where variation is so rife, it may take the form either of increase or 

 ofiUrrea.se in the nund.er of the teeth. In the former case the new 



