Very different was the Liodon dyspelor, a still larger animal than the last, with a formidable armature. It was indeed the longest of known reptiles, and probably equal to the great finner whale of modern oceans. 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, (Lieut. Jas. H. Whitten, U. S. A.), 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 carcass 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. The species of Clidastes did not reach such a size as some of the Liodons, and were of elegant and flexible build. To prevent their habits of coiling from dislocating the vertebral column, these had an additional pair of articulations at each end, while their muscular strength is attested by the elegant striæ and other sculptures which appear on all their bones. Three species of this genus occur in the Kansas strata, the largest (Clidastes cineriarum, Cope) reaching forty feet in length. The discovery of a related species (Holcodus coryphæus, Cope) was made by the writer under circumstances of difficulty peculiar to the plains. After examining the bluffs for half a day without result, a few bone fragments were found in a wash above their base. Others led the way to a ledge forty or fifty feet from both summit and foot, where, stretched along in the yellow chalk, lay the projecting portions of the whole monster. A considerable number of vertebræ were found preserved by the protective embrace of the roots of a small bush, and, when they were secured, the pick and knife were brought into requisition to remove the remainder. About this time one of the gales, so common in that region, sprang up, and, striking the bluff fairly, reflected itself upwards. So soon as the pick pulverized the rock, the limestone dust was carried into eyes, nose, and every available opening in the clothing. I was speedily blinded, and my aid disappeared into the canyon, and was seen no more while the work lasted. Only the enthusiasm of the student could have endured the discomfort, but to him it appeared a most unnecessary "conversion of force" that a geologist should be driven from the field by his own dust. A handkerchief tied over the face, and pierced by minute holes opposite the eyes, kept me from total blindness, though dirt in abundance penetrated the mask. But a fine relic of creative genius was extricated from its ancient bed, and one that leads its genus in size and explains its structure.
On another occasion, riding along a spur of a yellow chalk bluff, some vertebræ lying at its foot met my eye. An examination showed that the series entered the rock, and, on passing round to the opposite side the jaws and muzzle were seen projecting from it, as though laid bare for the convenience of the geologist. The spur was small and of soft material, and we speedily removed it in blocks, to the level of the reptile, and took out the remains, as they laid across the base from side to side. A genus related to the last is Edestosaurus. A species of thirty feet in length, and of elegant proportions has been called E. tortor (Cope.) Its slenderness of body was remarkable, and the large head was long and lance-shaped. Its flippers tapered elegantly, and the whole animal was more of a serpent than any other of its tribe. Its lithe movements brought many a fish to its knife-shaped teeth, which are more efficient and numerous than in any of its relatives. It was found coiled up beneath a ledge of rock, with its skull lying undisturbed in the center. A species distinguished for its small size and elegance is Clidastes pumilus (Marsh). This little fellow was only twelve feet in length, and was probably unable to avoid occasionally furnishing a meal for some of the rapacious fishes which abounded in the same ocean.
Tortoises were the boatmen of the cretaceous waters of the eastern coast, but none had been known from the deposits of Kansas until very recently. One species now on record (Protostega gigas, Cope), is of large size, and strange enough to excite the attention of naturalists. It is well known that the house or boat of the tortoise or turtle is formed by the expansion of the usual bones of the skeleton till they meet and unite, and thus become continuous. Thus the lower shell is formed of united ribs of the breast and breast-bone, with bone deposited in the skin. In the same way the roof is formed by the union of the ribs with bone deposited in the skin. In the very young tortoise the ribs are separate as in other animals; as they grow older they begin to expand at the upper side of the upper end, and, with increased age, the expansion extends throughout the length. The ribs first come in contact where the process commences, and in the land-tortoise they are united to the end. In the sea-turtle, the union ceases a little above the ends. The fragments of the Protostega were seen by one of the men projecting from a ledge of a low bluff. Their thinness and the distance to which they were traced excited my curiosity, and I straightway attacked the bank with the pick. After several square feet of rock had been removed, we cleared up one floor, and found ourselves well repaid. Many long slender pieces, of two inches in width, lay upon the ledge. They were evidently ribs, with the usual heads, but behind each head was a plate like the flattened bowl of a huge spoon placed crosswise. Beneath these stretched two broad plates two feet in width, and no thicker than binders' board. The edges were fingered, and the surface hard and smooth. All this was quite new among fully grown animals, and we at once determined that more ground must be explored, for further light. After picking away the bank and carving the soft rock, new masses of strange bones were disclosed. Some bones of a large paddle were recognized, and a leg bone. The shoulder-blade of a huge tortoise came next, and further examination showed that we had stumbled on the burial-place of one of the largest species of sea-turtle yet known. The single bones of the paddle were eight inches long, giving the spread of the expanded flippers as considerably over twenty feet. But the ribs were those of an ordinary turtle just born, and the great plates represented the bony deposit in the skin, which, commencing independently in modern turtles, united with the expanded ribs below, at an early day. But it was incredible that the largest of known turtles should be but just hatched, and for this and other reasons it has been concluded that this "ancient mariner" is one of those forms not uncommon in old days, whose incompleteness in some respects points to the truth of the belief, that animals have assumed their modern perfection, by a process of growth from more simple beginnings.
The cretaceous ocean of the West was no less remarkable for its fishes than for its reptiles. Sharks do not seem to have been so common as in the old Atlantic, but it swarmed with large predaceous forms related to the salmon and saury.
THE SEA WHICH ONCE COVERED THE PLAINS.
Elasmosaurus platyurus. 2. Liodon proriger. 3, 4, 5. Ornithochirus umbrosus. 6. Ornithochirus harpyia. 7. Protostega. 8. Polycotylus latipinnis.
Vertebræ and other fragments of these species project from the worn limestone in many places. I will call attention to, perhaps, the most formidable, as well as the most abundant of these. It is the one whose bones most frequently crowned knobs of shale, which had been left standing amid surrounding destruction. The density and hardness of the bones shed the rain off on either side, so that the radiating gutters and ravines finally isolated the rock mass from that surrounding. The head was some inches longer than that of a fully grown grizzly bear, and the jaws were deeper in proportion to their length. The muzzle was shorter and deeper than that of a bull-dog. The teeth were all sharp cylindric fangs, smooth and glistening, and of irregular size. At certain distances in each jaw they projected three inches above the gum, and were sunk one inch into the bony support, being thus as long as the fangs of a tiger, but more slender. Two such fangs crossed each other on each side of the middle of the front. This fish is known as Portheus molossus (Cope). Besides the smaller fishes, the reptiles no doubt supplied the demands of his appetite.
The ocean in which flourished this abundant and vigorous life, was at last completely inclosed on the west, by elevation of sea-bottom, so that it only communicated with the Atlantic and Pacific at the Gulf of Mexico and the Arctic Sea. The continued elevation of both eastern and western shores contracted its area, and when ridges of the sea-bottom reached the surface, forming long low bars, parts of the water area were inclosed and connection with salt water prevented. Thus were the living beings imprisoned and subjected to many new risks to life. The stronger could more readily capture the weaker, while the fishes would gradually perish through the constant freshening of the water. With the death of any considerable class the balance of food supply would be lost, and many larger species would disappear from the scene. The most omnivorous and enduring would longest resist the approach of starvation, but would finally yield to inexorable fate; the last one caught by the rising bottom among shallow pools from which his exhausted energies could not extricate him.
PART II—GEOLOGY.