[38] We retain the old spelling with the _e_ as being nearer to the Greek, although Professor Cope writes it "Liodon."
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 every fossil-hunter will appreciate. We, in England, who visit clay pits, stone quarries, railway cuttings, etc., during a morning or an afternoon walk, and return home at our leisure with a few small specimens in our pockets, or in a bag at our back, can hardly realise how arduous must be the work of finding, digging out, and transporting for such long distances the remains of the monsters of Kansas and other parts of North America.
[Illustration: Fig. 41.--Skeleton of _Clidastes cineriarum_; length 40 feet. (After Cope.)]
The following extracts have been selected from Professor Cope's report, with a view to illustrating the nature of the explorations undertaken. "The circumstances attending the discovery of one of these will always be a pleasant recollection to the writer. A part of the face, with teeth, was observed projecting from the side of a bluff by a companion in exploration, Lieutenant James H. Whitten, United States Army, and we at once proceeded to follow up the indication with knives and picks. Soon the lower jaws were uncovered, with their glistening teeth, and then the vertebræ and ribs. Our delight was at its height when the bones of the pelvis and part of the hind limb were laid bare, for they had never been seen before in the species, and scarcely in the order. While lying on the bottom of the Cretaceous sea, the carcase had been dragged hither and thither by the sharks and other rapacious animals, and the parts of the skeleton were displaced and gathered into a small area. The massive tail stretched away into the bluff, and, after much laborious excavation, we left a portion of it to more persevering explorers."