24 
CENTRAL HALL. 
to display not only the shape of the crowns, but also the 
number and character of the roots by which they are implanted. 
Bay II. In bay No. II. the two wall-cases contain a collection ar- 
Classification ranged to show in a serial manner the generally recognised 
orders and sub-orders of existing Mammals, by examples 
selected to illustrate the predominating characters by which 
these are distinguished. A brief popular account of the 
characteristics of the group, and a map showing its geographical 
distribution, are 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 adopted in smaller institutions. 
Among the illustrations of the order Primates is placed the 
skeleton of a young Chimpanzee dissected by Dr. Tyson, 
which formed the subject of his work on the " Anatomy of a 
Pigmie," published in 1699, the earliest scientific description 
of any Man-like Ape. 
Skin The central case of this bay contains illustrations of the 
of Mammals. ^^^^^ covering or skin 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 jdevelopment of 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 gigantic extinct species 
iGlyptodon) shows a bony external as well as an 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 Manidce. 
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. 
5. The special epidermal appendages found in nearly all 
Mammals on the ends of the fingers and toes, called according 
to the various forms they assume, nails, claws, or hoofs. 
6. The one or two unpaired horns of the Ehinoceroses, shown 
