194 EXTINCT MONSTERS 
considerable speed. Like snakes, they were furnished with four 
rows of formidable teeth on the roof of the mouth, which served 
admirably for seizing their prey. 
But the most remarkable feature in these creatures was the 
arrangement for permitting them to swallow their prey whole, 
in the manner of snakes. Thus each half of the lower jaw was 
articulated at a point nearly midway between the ear and the 
chin, so as to greatly widen the space between the jaws, and 
Professor Cope thinks that the throat must consequently have 
been loose and baggy. 
Professor Cope, however, in giving the name Pythonomorpha 
to this ancient group, has pressed his views too far, and dwelt 
unduly on their supposed relationship with serpents. Other 
authorities regard them as essentially swimming lizards, with 
four well-developed paddles; and this is probably the right view 
to take of them. 
“Tf, as appears certain,” says the Professor, “ the Mosasauroid, 
discovered by Webb, measures seventy-five feet in length, and 
the M. maximus, eighty, the Leiodon dyspelor must have been the 
longest reptile known, and approaches very nearly the extreme 
of the mammalian growth seen in the whales, though, of course, 
without their bulk. Such monsters may well excite our surprise, 
as well as our curiosity, in the inquiry as to their source of food- 
supply, and the character of those contemporary animals preserved 
on the same geological horizon.” 
According to Dr. 8. W. Williston, who has, of late years, dis- 
covered and described most valuable specimens of Mosasauroid 
reptiles, Clidastes had a skull less flattened than that shown in 
some earlier restorations (¢.g. in the previous edition of this book) 
and the digits were curved, as in Platycarpus. Of the former 
reptile, which was forty feet long, a single specimen was 
