132 EXTINCT MONSTERS. 
With regard to the place of Pterodactyls in the animal kingdom, 
Professor Seeley places them as a distinct sub-class, side by side 
with birds, and between mammals and reptiles, thus— 
Mammalia. 
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Reptilia. 
The name Ornithosauria (bird-lizards) is frequently used 
instead of the other name, because it expresses the idea of their 
being partly saurian, and partly bird-like. 
They flourished from the period of the Lias to that of the 
Chalk ; and then, like so many other strange forms, seem to 
have suddenly disappeared. 
