TYPES OF MAMMALS. 21 



the riglit side reserved for the exhibition of recently acquired 

 specimens of especial interest) devoted t6 the Introductory or 

 Elementary Morphological Collection, designed to illustrate the 

 more important points in the structure of certain types of 

 animal and plant life, and the terms used in describing them. 

 This has been called the " Index Museum," as it was thought at 

 one time that it would form a sort of epitome or index of the 

 main collections in the galleries ; but the name does not exactly 

 express that into which it has developed. It is really more 

 like the general introduction preceding the systematic portion 

 of treatises on any branch of natural history. The space being 

 limited, the number of specimens is necessarily restricted. In 

 examining this collection the visitor should follow each case in 

 the usual order of reading a book, from left to right, and should 

 carefully study the printed explanatory labels, to which the 

 specimens are intended to serve as illustrations. 



The bays on the west side (left-hand on entering the haU) are 

 devoted to the Vertebrated Animals, or those possessing a 

 "backbone." In Nos. I. and II. are shown the characters of 

 the Mammals, which form the highest modification of this type. 

 The wall-cases of ^STo. I. contain specimens showing the bony 

 framework (internal skeleton) of Mammals. 



In the first case (south side of the recess) wiU be seen a Bay i. 

 complete skeleton of a good example t)f the class — a Baboon Skeleton of 

 Monkey, with all the bones separated, laid out on a tablet, and 

 their names affixed to them. Below is a skeleton of the 

 same animal articulated, or with the bones in their natural 

 relation to each other, and also named. By examining these 

 two specimens an idea may be obtaiaed of the general frame- 

 work of the bodies of animals of this class. In other parts of 

 the case are placed examples of modifications of the skeleton 

 to suit different conditions of life. 



1. Man, showing a skeleton adapted for the upright 

 position. 



2. A Bat, or flying Mammal, in which, by the great elonga- 

 tion of the fingers, the fore-limbs are converted into wings 

 (fig. 7), supporting a web of skin stretched between them. 



3. A Sloth, in which the tips of both limbs are reduced to 

 mere hooks, by whose aid the creature hangs back-downwards 



