THE CRETACEOUS PERIOD. 279 
which it very closely resembles, appears to have walked upon 
its hind-legs, the fore-limbs being disproportionately small. 
Another remarkable group of Reptiles, exclusively confined 
to the Cretaceous series, is that of the A/osasauroids, so called 
from the type-genus Josasaurus. The first species of J/osa- 
saurus known to science was the JZ. Camperi (fig. 210), the 
Fig, 210.—Skull of Mosasaurus Camperi, greatly reduced. Maestricht Chalk. 
skull of which—six feet in length—was discovered in 1780 in 
the Maestricht Chalk at Maestricht. As this town stands on 
the river Meuse, the name of MJ/osasaurus (“ Lizard of the 
Meuse”) was applied to this immense Reptile. Of late years 
the remains of a large number of Reptiles more or less closely 
related to Mosasaurus, or absolutely belonging to it, have been 
discovered in the Cretaceous deposits of North America, and 
have been described by Professors Cope and Marsh. All 
the known forms of this group appear to have been of large 
size—one of them, Mosasaurus princeps, attaining the length of 
‘seventy-five or eighty feet, and thus rivalling the largest of ex- 
isting Whales in its dimensions. The teeth in the “ Mosa- 
sauroids” are long, pointed, and slightly curved ; and instead 
of being sunk in distinct sockets, they are firmly amalgamated 
with the jaws, as in modern Lizards. The palate also carried 
teeth, and the lower jaw was so constructed as to allow of the 
mouth being opened to an immense width, somewhat as in the 
living Serpents. The body was long and snake-like, with a 
very long tail, which is laterally compressed, and must have 
served as a powerful swimming-apparatus. In addition to this, 
both pairs of limbs have the bones connecting them with the 
