46 DE EAE AN DI CUASS LE CATON CHAP. 
maxilla. There are no vomerine, 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 lghtest 
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 Bussariscus, 
which Sir W. Flower showed to be a Raccoon, is in its teeth a 
Viverrid. Mr. Bateson has been obliged to hamper the subject 
with another difficulty. 
In dealing with the variations of teeth,’ 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 fontaniert, 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. 
