46 TEETH AND CLASSIFICATION CHAP. 



maxilla. There are no vomeriue, palatine, or pterygoid teeth, 

 such as are met with in Amphibia and Reptilia. 



The other peculiarities of the mammalian teeth, though true 

 of the great majority of cases, are none of them absolutely 

 universal. 



But it is necessary to go into the subject at some length on 

 account of the great importance which has been laid upon the 

 teeth in deciding questions of relationship ; moreover, largely no 

 doubt on account of their hardness and imperishability, our 

 knowledge of certain extinct forms of Mammalia is entirely based 

 upon a few scattered teeth ; while of some others, notably of 

 the Triassic and Jurassic genera, there is not a great deal of 

 evidence except that which is furnished by the teeth. Indeed 

 the important place which odontography holds in comparative 

 anatomy is from many points of view to be regretted, though 

 inevitable. " In hardly any other system of organs of verte- 

 brated animals," remarks Dr. Leche, " is there so much danger of 

 confounding the results of convergence of development with true 

 homologies, for scarcely any other set of organs is less con- 

 servative and more completely subservient to the lightest 

 impulse from without." Affinities as indicated by the teeth are 

 sometimes in direct contradiction to those afforded by other 

 organs ; or, as in the case of the simple Toothed Whales, no 

 evidence of any kind is forthcoming. Dr. Leche has pointed out 

 that, judged merely from its teeth, Arctictis would be referred to 

 the Raccoons, though it is really a Viverrid ; while Bassariscus, 

 which Sir W. Flower showed to be a Raccoon, is in its teeth a 

 Viverrid. Mr. Batesoii has been obliged to hamper the subject 

 with another difficulty. 



In dealing with the variations of teeth, 1 Mr. Bateson has 

 brought together an immense number of facts, which tend to 

 prove that the variability of these structures is much greater than 

 had been previously recognised ; that this variability is often 

 symmetrical ; and that in some animals, as in " Canis cancrivorus, 

 a South American fox, the majority showed some abnormality." 

 When we learn from Mr. Bateson that " of Felis fontanieri, an 

 aberrant leopard, two skulls only are known, both showing dental 

 abnormalities," it seems dangerous to rear too lofty a super- 

 structure upon a single fossil jaw. It must be noted too that, 



1 Materials for the Study of Variation, London, 1894. 



