20 
CENTRAL HALL. 
labels attached to them. The under surfaces of the skulls of 
various birds are shown with the different bones coloured to 
indicate their limits and relations ; these being followed by a 
series of the different types of sternum or breast-bone. 
The second wall-case contains further illustrations of the 
anatomy of birds, including a series arranged to show the general 
characters of the eggs of this class, as exemplified in their struc- 
ture, number, form, size, texture of surface and colour. In the 
upper part are a series of wings of birds displaying the form 
characteristic of different groups ; while below are a few of the 
different types of tails. Very instructive is a series of skins of 
white chickens of the same brood at different ages displaying 
the gradual replacement of the down by the adult plumage. 
The table-case in the middle of the bay contains illustra- 
tions of the external characters, the beak, the feathers, and the 
tail, as well as of the fore and hind limbs, or wings and feet. 
By the aid of the explanatory labels, the essential characters 
and the principal modifications of all these parts can easily 
be followed. 
Bay IV. The fourth bay on the west side of the hall exhibits the 
^rT^of leading peculiarities in the structure of Eep tiles and Amphi- 
Reptiles and bians. Owing to the large number of groups in the former 
Amphibians, q^s^ss which are now extinct, many fossil specimens, or plaster 
reproductions of the same, are shown. The wall-case on the 
south side of this bay illustrates the different ordinal groups of 
reptiles — living and extinct. Yery instructive are the skeletons 
of Tortoises and Turtles, showing the relations of the vertebrae 
and limb-bones to the bony shell. Lizards and Snakes are 
mostly represented by coloured casts, as being best adapted 
for exhibition purposes. The extinct Dinosaurs are represented 
by a small- sized model of the Iguanodon, together with a 
photograph of the skeleton and a plaster-cast of the bones of 
the hind-foot showing the three toes. 
The adjacent side of the table-case shows the modifications 
of the backbone, or vertebral column, of the ribs, and of the 
limbs, in the different groups of the class. Specially noticeable 
are examples of five types of Scincoid Lizards, exhibiting the 
gradual diminution in the size of the limbs and their final 
disappearance. 
