REPTILIA. 
7 
ment of its parts it bears a most striking resemblance to the Wall-ease 
brain of a bird. The neck is stout and mobile, its large verte- ip a ^i e ^c ases 
brie being united by ball-and-socket joints, in which the ball i_ 4 . 
is posterior. The body is relatively small, and the tail varies l>. 
in extent, being sometimes long and slender, sometimes very 
short. The wings are disproportionately large, and the wing- 
membrane is supported by the much-elongated fifth finger, 
while the other fingers remain small or even rudimentary. 
The breast-bone is expanded as in birds, and keeled in front 
to accommodate the muscles for flapping the wings. The 
hind limbs are weak, and four of the slender toes bear claws. 
No armour of any kind has been noticed even in the finest 
known specimens from the Lithographic Stone of Bavaria, 
which exhibit clear impressions of the smooth wing 
membrane. 
The latest Pterodactyls are the largest, and are best 
Pig. 3. —Skeleton of a toothless Flying Reptile (Pteranodon occidentalis), 
from the Upper Cretaceous of Kansas, U.S.A.; about one fifty-fourth 
nat. size. (Wall-case 2.) 
known by skeletons from the Chalk of Kansas. They are 
well illustrated by a fine pair of wings of Pteranodon , which 
are mounted on a picture of the complete skeleton in Wall- 
case 2 (Fig. 3). The outlines and proportions of the bones 
painted in this picture are based partly on specimens in 
American museums, partly on imperfect remains in 'Table- 
cases 3, 4. The jaws form a sharp, toothless beak, and the 
head rises behind into a prominent crest. The breast-bone 
is short and broad, with the keel in front; and the shoulder- 
blade on each side is firmly fixed to the backbone to 
strengthen the socket in which the wing works. The wing- 
fingers, of which the actual bones are shown, are immense, 
and the supposed extent of the membrane they originally 
supported is indicated by colour. The total expanse of 
the wings is about eighteen feet, and it is thought that the 
