THE GREAT SEA-LIZARDS AND THEIR ALLIES. 55 
to ten feet in length. But in the rocks of the Cretaceous period, 
which was later, are found larger specimens. There is a cast of a 
very fine specimen from the Upper Lias on the wall of the east 
corridor (No. 3 on Plan) of the geological galleries at South 
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Fic. 7.—Mandibles of Fish-lizards. Aa, Feloneustes philarchus (Seeley) ; 
from the Oxford Clay. 3B, Thaumatosaurus indicus (Lydekker); Upper 
Jurassic of India. c, Plestosaurus dolichodirus (Conybeare) ; from the 
Lower Lias, Lyme Regis. 
Kensington, which is twenty-two feet long. But some of the 
Cretaceous forms, both in Europe and America, attained a length 
of forty feet, and had vertebre six inches in diameter. The 
bodies of the vertebrze, or “ cup-bones,” are either flat or slightly 
