24 
CENTRAL HALL. 
with their names affixed to them. Below it 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 a fair idea may be obtained of the general frame- 
work of the body 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 the fore-limbs are 
converted into wings by the great elongation of the fingers, 
which support a web of skin stretched between them. 
Bay I. 3. A Sloth, in which the ends of all the limbs are reduced to 
Skeleton of niere hooks, by which the creature hangs back-downwards from 
Mammals. , , . . 
the boughs of the trees among which it passes its entire existence. 
4. The Baboon serves as an example of an animal walking on 
all four limbs in the "plantigrade" position, i.e., with the whole of 
the palms of the hands and soles of the feet applied to the ground. 
5. A small species of Antelope shows the characteristic form 
of a running animal, in which the limbs perform no office but 
that of supporting the body on the ground. It stands on the 
tips of the toes of its elongated slender feet. 
6. A Porpoise, adapted solely for swimming in the water. 
The fore limbs are converted into flattened paddles, and the 
hind limbs are entirely absent, their function being performed 
by the tail. The rudimentary pelvic bones are preserved. 
The rest of the case is occupied by details of the skull in some 
of its principal modifications. At the top are diagrams of the 
structure of bone and cartilage as shown by the microscope. 
In the wall-case on the opposite (north) side of the bay the 
outline of the osteology of mammals is continued by illustrations 
of the structure of the limbs. At the top of the case is a 
diagram showing the correspondence of the hand and the foot 
in its complete typical form, with the names applied by 
anatomists to the different bones. The series of specimens 
below show the principal deviations which actually occur from 
the typical condition, which, as will be seen, is very nearly 
preserved in the human hand. One interesting series shows 
some of the stages of modification for special purpose (specializa- 
tion) by which a typical five-fingered hand becomes converted 
