144 EXTINCT MONSTERS. 



followed as far as time would permit, but part of the tail series 

 had to be left. In size, the vertebrae of this enormous sea-serpent 

 exceed those of Mosasaurus brumbyi. The latter has hitherto 

 been the largest known species of the order of Pythonomorphs, 

 exceeding twofold in its measurements the M. giganteus of 

 Belgium. So the present reptile is much larger in its dimensions 

 than the New Jersey species called maximus by Professor Cope. 

 " If, as appears certain," says the professor, " the Mosasauroid 

 discovered by Webb measures seventy-five feet in length, and the 

 M. maximus measured 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 what the character of those contemporary 

 animals preserved in the same geologic horizon." 



In our illustration, Plate XIII., the artist Jias endeavoured to 

 realise the outward aspect of the two genera of sea-serpents, 

 Mosasaurus and Clidastes. The fishes which they are pursuing 

 are well-known genera from the English Chalk, such as Beryx. 



Ten species of Clidastes have been unearthed from the Kansas 

 strata. They did not reach such a size as the Leiodons, but 

 were of elegant and flexible build, the largest species, C. 

 cineriarum, reaching a length of forty feet (see Fig. 41). A 

 smaller species, of elegant proportions, has been called C. tortor 

 (Cope). Its slenderness of body was remarkable, and the large 

 head was long and lance-shaped. Its lithe movements doubtless 

 helped it to secure many fishes. It was found coiled up 

 beneath a ledge of rock, with its skull lying undisturbed in the 

 centre. 



The accounts given by Professor Cope of his explorations and 

 the difficulties encountered in procuring the valuable specimens on 

 which his conclusions are based, are most interesting, and such as 



