COMPARATIVE ANATOMY OF TEETH. 
29 
SOME POINTS OF INTEREST IN THE COMPARATIVE 
ANATOMY OF TEETH * 
By Henry Blandy, L.D.S. Edin. 
It is a great advantage to the naturalist if lie understands 
what is expressed by a tooth, should he happen to find one. 
You have only to present to the comparative anatomist and 
palaeontologist a fossil tooth which has perchance been buried 
in some cave for thousands of years, and he will, perhaps, be 
able, from the consideration of its formation, to build up and 
sketch out the animal from whose head it has come. In 
this way many of the extinct saurians and mammoths of 
pre-historic times have been recognised and allied to the 
reptilia or pachydermata. 
Speaking roughly, the teeth of animals may be divided 
into two great classes—the graminivorous or grain-eating 
vegetable-feeding animals, and the carnivorous or flesh-eating 
animals. Between these two is an almost infinite variety 
of gradations in form and structure. The teeth of the 
graminivores are flat and broad—adapted for grinding—such 
as those of the elephant, cow, sheep, and horse, whose lower 
jaws have considerable lateral motion. Those of the carnivora 
bite like scissors, and are cutting or chopping teeth. You 
will have observed that dogs and cats do not chew their food 
much. Now, the pig is an all-round feeder. He will eat 
flesh and grain, too ; nothing comes amiss to him. He will 
even eat coal—perhaps because it is of vegetable origin ; and 
we find his molars are broad for this scrunching, but they 
have cusps like the carnivora, and are very much more like 
man’s teeth than are either cow’s or lion’s. Then, again, the 
rodents, or rats, have a pattern of their own. So have the 
insect eaters, snakes, and fish ; and as teeth differ in form, 
so also do they differ widely in microscopic structure. So 
that, although there are certain homologies in teeth, there are 
also unmistakeable differences. 
When you see a tooth, before you could attempt to decide 
finally whose it is, you would have to decide which tooth it was 
—whether an incisor, canine, premolar, or molar— and which ; 
and you would proceed by elimination. Some animals have 
no upper incisors, as sheep, oxen, and antelopes; while 
some have no canine teeth, as rodents, hares, rabbits, 
rats, etc. If the tooth belonged to a quadruped, there are 
sufficient distinctive characteristics to enable a skilled 
odontologist to identify it; while if the tooth belonged to 
a reptile or fish there would be much greater difficulty, 
* Read before the Nottingham Naturalists’ Society, Nov. 6, 1883, 
