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THE COMPARATIVE ANATOMY OF THE
TEETH OF THE VERTEBRATA.

By JACOB L. WOBTMAN, A. M., M. D.

A STUDY of the dental organs of the Vertebrata is one replete with
much interest when viewed from the standpoint of the naturalist. The
circumstance that their modification is so intimately associatetl with the
food-habits of the animal, being principally concerned in the prehension
and comminution of the food, and that to these same habits we must
look for the most powerful influences and incentives to modification in
general, causes them to assume more than ordinary importance in the
estimation of the philosophic anatomist who earnestly addresses himself
to the pi'oblem of vertebrate evolution.
The fact, too, that the perfect condition in which they have been so ofter*
preserved in the fossiliferous strata of the earth's crust has frequently
furnished the only evidence which we possess of the existence of forms
long since extinct, causes them to be regarded as objects of still greater
interest. When we reflect that with nothing more to guide his judg-
ment than the dental series of an animal the expert palaeontologist can,
generally, not only indicate with great certainty the character of the
food upon which the animal subsisted, but its general characteristics
and relationships as well, even though the date of its existence be
removed to a remote period in geologic history, but little surprise
can be felt that so much thoughtful attention has been bestowed
upon this set of organs.
No series of anatomical structures has proved of greater utility to the
systematist who has endeavored to indicate the exact relationship or
philogenetic history of mammalian forms than the teeth. Generally,
the student who attempts to master the subject is discouraged almost at
the very threshold of his undertaking by the apparently great diversity
of tooth-forms to be met with in the mammalian class ; but if looked
at from a developmental point of view, and if a little careful attention
is bestowed upon the plan of organization of the teeth of certain groups,
it is not difficult to discover that there are certain central or primitive
types from which it is easy to derive other related forms of dentition
by simple addition, subtraction, or modification of parts already pos-
sessed.
Careful attention to this subject for several years past, with the assist-
ance of the light which American palaeontology is now able to throw
n])on the question, has convinced me more and more of the truth of
this assertion ; and I feel well assured that we are now in a position to
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