THE SERPEXTLIKE SEA SAURIANS. 211 



approacliiiig, they swam away with incredible speed. A flock of 

 them must have resembled the shipping of a harbor with tall masts 

 yellowing in the sunlight. At the base of the long necks were ele- 

 phantine bodies, and behind, long, tapering tails. Forward and be- 

 hind were two sets of paddles, perhaps terminating with webbed 

 digits. With the forward paddles Cope thought that they might 

 have seized prey; with all four paddles they swam. From thirty to 

 sixty feet in length, they were well adapted to the deepest waters and 

 to breast the waves of the seas. Like swans and Floridian snake birds, 

 they plunged their necks downward for prey, the body perhaps re- 

 maining on the surface as an anchor. Carnivorous, the elasmosaur 

 ate what it could seize, and to-day, with its bones, are found the 

 bones of its victims, usually fishes. Somewhat similar were the 

 cimoliosaurs, even longer necked at times, but with shorter and 

 more powerful tails. 'J.lieir paddles were long, and as swimmers they 

 must have had few equals in speed. Smooth silicious pebbles to the 

 amount of a peck or two have been found in numerous instances 

 associated with the remains of plesiosaurs of various kinds. They 

 evidently formed a part of the contents of their stomachs, but their 

 use is not clear. But the real rulers of the Cretaceous ocean were 

 the pythonomorphs, or mosasaurs, more like the typical serpents of 

 to-day, and more entitled to be called sea serpents. 



The mosasaurs were more elongated and graceful in form. Their 

 heads were large, flat, and conical, with the eyes directed later- 

 ally. The tails were long. They had fore and aft paddles with 

 webbed digits, attached to the body with wide peduncles. With 

 paddles and flattened tails they swam with ease and speed. Like 

 snakes, they had four rows of formidable teeth on the roof of the 

 mouth, not for mastication, but for seizing prey and holding it. Like 

 snakes, they swallowed their prey entire, but, unlike snakes, they 

 had not elastic throats. The jaw was, however, so articulated, 

 jointed so far back between the ear and chin, ball-and-socket 

 fashion, that the immense opening made up for the lack of expansi- 

 bility of throat. The ends of the jaws were bound by flexible liga- 

 ments, permitting the passage of large fish or other prey. The mouth 

 of the gullet was prolonged forward while swallowing, evidently 

 being loose and baggy. The same habit pushed forward the glottis, 

 or opening of the windpipe in front of the gullet. Like a serpent, 

 the mosasaur hissed, owing to these formations. The tongue was 

 long and forked, and when at rest was inclosed in a sheath beneath 

 the windpipe and thrown out when the jaws were in motion. And 

 thus, too, are the nearest living forms. 



The mosasaurs attained great length, reaching from ten to fifty 

 feet. They had long, projecting muzzles, somewhat like that of the 



