144 EXTINCT MONSTERS. 
followed as far as time would permit, but part of the tail series 
had to be left. In size, the vertebree 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. 
‘“‘ Tf, 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 has 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 
