INTRODUCTION.
Teeth are firm substances attached to the parietes of the beginning
of the alimentary canal, adapted for seizing, lacerating, dividing
and triturating the food, and are the chief agents in the mechanical
part of the digestive function.
As secondary uses, arising out of the relations of co-existence
with other organs and endowments, or from a special development
of the teeth themselves, may be cited their. subserviency to
speech(l), as ornaments, as characterizing age and sex(2), as in-
flictors of wounds either in combat (3) or defence (4), as aids to
locomotion(5), means of anchorage(6), implements of transport and
for working of building materials(7).
The dental system thus presents many and peculiar attractions
to the anatomist and naturalist, for independently of the variety,
heauty and even occasional singularity of the form and structure
of the teeth themselves, they are so intimately related to the
food and habits of the animal as to become important if not essential
aids to the classification of existing species.
And, while the value of dental characters is enhanced by the
facility with which, from the position of the teeth, they may be
ascertained in living or recent animals, the durability of the teeth
renders them not less available to the Palaeontologist in the determi-
(1) Man. (2 ) Orang, Narwhal. (3) Dog. (4) Elephant, Musk-deer. (5) Morse.
(6) Dinothere. (7) Beaver.
a