INTRODUCTORY COLLECTIOX. 
29 
case is taken up by select examples of the dentition of all the 
different families of mammals arranged in systematic order, 
prepared so as to display not only the shape of the crowns, but 
also the number and character of the roots by which they are 
implanted. 
Bay ISTo. II. The two wall-cases contain a collection arranged Bay ii. 
so as to show in a synoptical manner the generally I'ecognised JJ^^^^^^^^ 
orders and sub-orders of existing Mammals, by examples 
specially selected to illustrate the predominating characters by 
which they are distinguished. A brief popular account of the 
characteristics of the group, and a map showing its geographical 
distribution, is placed with each. This is intended not only for 
an introduction to the study of the class by visitors to the 
museum, but also as a guide to a method of arrangement which 
may be advantageously adopted in other institutions of com- 
paratively limited resources. 
Among the illustrations of the order Pinmates is placed the 
skeleton of the young Chimpanzee, dissected by Dr. Tyson, and 
which formed the subject of his remarkable work on the 
Anatomy of a Pigmie/' published in 1699, the earliest scien- 
tific description of any man-like ape. 
The central case of this bay contains illustrations of the Integument 
outer covering or integument and its modifications in the class 
of Mammals, divided into the following sections : 
1. Expansion of skin to aid in locomotion, as the webs 
between the fingers of swimming and flying animals, the para- 
chutes of flying animals. 
2. The development of true bony plates in the skin, found 
among mammals only in the Armadillos and their allies. The 
cast of a section of the tail of a great extinct species 
{Gly]ptodon) shows well a bony external as well as internal 
skeleton. 
3. The outer covering modified into true scales, much resem- 
bling in structure the nails of the human hand. This occurs 
in only one family of mammals, the Pangolins or Manidcc. 
4. Hair in various forms, including bristles and spines. The 
two kinds of hair composing the external clothing of most 
mammals, the long, stiffer outer hair, and the short, soft under 
fur, are shown by various examples. 
