FLYING FLAGONS. 
39 
statement that an immature skull of one of the species measures upwards of 6 feet, 
while fully adult ones must have been considerably larger. The extraordinarily 
small size of the brain of these creatures is indicated in the lower figure of 
the skull. Externally the bodies of these dinosaurs were protected by granules 
and plates of bones, which, 
like those of crocodiles, were 
probably overlain with horny 
shields. It has yet to be 
mentioned that in the horned 
dinosaurs, as shown in the 
figure of the skeleton, the 
posterior bar of the pubis has 
disappeared, and only the 
front branch remains, thus 
causing the whole pelvis to 
simulate that of the carnivorous group, to which it has no real resemblance. 
We have yet to learn the reason why, at the close of the Secondary period, 
these mighty dinosaurs, together with the flying dragons which at the same time 
tenanted the air, and the fish-lizards and plesiosaurs which peopled the sea, should, 
one and all, disappear—and that apparently suddenly—to make way for mammals 
and birds, which henceforth became the lords of creation. 
RESTORATION OF THE SKELETON OF A HORNED DINOSAUR. 
pd, chin-bone. Other letters as in the figure on p. 4.—After Marsh. 
Flying Dragons, or Pterodactyles. 
Order Ornithosauria. 
At the present day bats and birds are the only Vertebrates endued with the 
power of true flight, but during the Secondary period, when the former were 
unknown and the latter but poorly represented, the place of both was taken by 
the flying dragons, or, as they are called, from the structure of their wings, 
Pterodactyles. While agreeing with crocodiles in the essential structure of their 
skulls and in their two-headed ribs, these curious reptiles have the other portions 
of their skeleton more or less specially modified for the purposes of flight. In the 
relatively large size of the brain—which is doubtless essential for a flying animal 
—and general bird-like form of the skull, as well as in the keeled breast-bone and 
general form of the collar-bones (although these are not welded together into a 
furcula), the pterodactyles present a curious similarity to birds. Misled by these 
resemblances, some anatomists have, indeed, been induced to consider that the 
two groups are nearly related, although a more mistaken notion never existed. 
Such resemblances as do exist between the two groups are due, indeed, to that 
parallelism in development to which we have already had occasion to call atten¬ 
tion as existing between totally different groups of animals whose mode of life 
is similar. 
The most distinctive feature of the pterodactyles is to be found in the 
modifications of the bones of the fore-limbs for the purpose of supporting a wing, 
which took the form of a membranous expansion of skin analogous to that con- 
