SEA-SERPENTS. 
141 
denizens of land?” These creatures lived in the Cretaceous 
period. The remains found in this region were mostly those of 
reptiles and fishes. Thirty-five species of reptiles are known 
from Kansas alone, representing six orders, and varying in 
length from ten to eighty feet. One was terrestrial, four were 
fliers, the rest inhabited the ocean. ‘^When they swam over 
what are now the plains, the coast-line extended from Arkansas 
to near Fort Riley, on the Kansas River, and, passing a little east- 
ward, traversed Minnesota to the British possessions, near the head 
of Lake Superior. The extent of sea to the westward was vast, 
and geology has not yet laid down its boundary ; it was probably 
a shore now submerged beneath the waters of the North Pacific.” 
Other very elongated marine reptiles of this period, but with 
much thicker bodies, are called, by Professor Cope, Elasmosaurs. 
In this group, which is not yet fully worked out, occur such 
genera as Cimoliosaurus, Polycotylus, Polyptychodon, and others. 
But it seems a pity that they should be in any way separated 
from the Plesiosaurs, which they strongly resemble (see chap, iv., 
Plate III.). Though not sea-serpents, we have introduced them 
here because they flourished at the same time, and lived in the 
same seas with the Mosasaurs and other forms of that group. The 
very large teeth, with strongly marked ridges, of the Polyptychodon 
are abundant in the Cambridge Greensand that underlies the 
chalk, and represent a very huge animal. 
In our illustration, Plate XIIL, the artist has represented 
the Elasmosaurus^ (of Cope) with its long thin neck stretched 
out in search of food on the bed of the sea. Professor Cope — 
thus describing this monster, in language which seems some- 
what fanciful — says, “ Far out on the expanse of this ancient 
sea might have been seen a huge snake-like form, which rose 
above the surface, and stood erect, with tapering throat and 
arrow-shaped head, or swayed about, describing a circle of 
^ Greek — elasmos, plate ; sauros^ lizard : probably on account of the shape 
of the paddles. 
