1892.] NUMERICAL VARIATION IN TEETH. 105 



panzee, and Gorilla — 141 normal skulls were seen, and 1 1 cases 

 of supernumerary teeth, or nearly 8 per cent, (in addition 

 to 7 recorded cases known to me). On the other hand, no 

 case was seen in .51 skulls of Hylohates, which were all normal. 

 And of Old World Monkeys other than these, I found only 

 two cases in 423 skulls, or less than '5 per cent. 



In the species of Cebidse and in Ateles supernumerary 

 teeth are common, five cases being found, in 131 skulls, or 

 nearly 4 per cent, (in addition to 4 recorded cases) ; while in 

 92 skulls of other New World Monkeys there was not one case. 



Phocid^e. — 139 normals, 11 cases of supernumerary teeth, or 

 7'5 per cent. 



Otariid^e.- — 121 normals, 5 cases of supernumerary teeth, or 

 4 per cent. 



Canid^. — Of wild Canidse, 289 normals were seen, and 9 cases of 

 supernumerary teeth, or 3 per cent, (in addition to numerous 

 recorded cases). 



Of Domestic Dogs, including Pariahs, &c., 200 skulls were 

 normal and 16 had supernumerary teeth, or 8 per cent, 

 (besides many recorded cases). 



Felid^. — Of wild Felidse, 2/8 normals and 6 cases of super- 

 numerary teeth, or more than 2 per cent. 



Of Domestic Cats, 35 normal and 3 cases of supernu- 

 merary teeth, or 9 per cent. 



ViVERRiD^. — 94 normals (not regarding variations affecting the 

 first premolar only) and 4 cases of supernumerary teeth. 



Owing to the great variability of the dentition of some groups of 

 Marsupials and the difficulty of deciding on the normal formula, it 

 would not be profitable to give summary statistics which should be 

 satisfactory. 



It will be seen that, so far as the statistics go, supernumerary 

 teeth were more common in domestic Dogs than in wild Canidae, 

 and though the number of Cats seen was small, the same is true in 

 their case also as compared with wild Felidse. But though it is 

 received by many almost as an axiom that domestic animals are, as 

 such, more variable than wild ones, and though the figures some- 

 what support this view, it is necessary to point out that such a 

 deduction should be made with great caution. For while it is true 

 that the domestic Dog is more variable in its dentition than wild 

 Dogs, it is not true that it is much more variable than many other 

 wild animals, as, for example, the xlnthropoid Apes, some of the 

 Phocidse, several genera of Marsupials, and others. The doctrine 

 that domestication induces or causes Variation is one which will not, 

 I think, be maintained in the light of fuller evidence as to the 

 Variation of wild animals. It has been suggested by the circumstance 

 that so many of our domesticated animals are variable forms, and that 

 so little heed has been paid to the variation of wild forms. To obtain 

 any just view of the matter, the case of variable domestic species 

 should be compared with a species which is variable though wild. 



