MEDIEVAL OR MESOZOIC TIMES, 193 



nearly midway between the base and the anterior end.- This joint 

 was of the ball and socket type, which enabled it to make an angle 

 outward, and thus greatly to widen the space between the two* 

 halves. This arrangement, in fact, seems to have anticipated that 

 of the arms, which can be made to imitate it by placing the hands 

 close together, extended forward and with the elbows bowed out.- 

 The ends of the bones, like in the serpents, were only bound to- 

 gether by flexible ligaments. This posture of the arms gives a 

 diamond shaped space, and represents the expansion practiced in 

 these reptiles to enable the passage of a large fish or other victim. 

 The arms only represent the size of the jaws of the smaller species, 

 the larger ones being much more extended. The basal half of 

 the jaw, like in all other reptiles, is attached by a column-like 

 bone (quadrate bone), whose shape and form varies a great 

 deal in the different species, being dependent on the degree of 

 twist to be allowed or needed. In consequence of this peculiar 

 structure, the mouth of the gullet must have been prolonged for- 

 ward, and the throat must also have been loose and baggy like that 

 of a pelican. Such a structure would also necessitate the throwing 

 forward the opening of the wind pipe or glottis, as this is always 

 in front of the gullet. The tongue must also have been far for- 

 ward, long and forked. The only noise that could have been made 

 by such an animal would be a hiss like in the serpents, but a hiss 

 which for loudness would resemble distant thunder. They were 

 furnished with two pairs of huge paddles "which were attached to 

 the body by short peduncles." Their tails were flattened, but their 

 strokes, aided by the paddles, must have sent them through the 

 water with great velocity. 



The most gigantic of these reptiles (Liodon proriger, Cope), at- 

 tained a length of not less than seventy-five feet, and probably 

 much greater. This species was very abundant. It had a long, 

 projecting muzzle, remotely resembling that of the Atlantic blunt- 

 nosed sturgeon, but the ends of the lower jaw were much more 

 blunt and massive. Such an arrangement must have made it a 

 terrible ram, and no doubt it often stunned its victims by a butt 

 before swallowing them. Liodon dyspelar, Cope, was perhaps 

 equally as large as the preceding, but by no means so abundant. 

 Two somewhat smaller species of Liodon occupied the same seas. 



A genus closely related to the last, and whose remains are 

 specially abundant in Nebraska, is Clidastes. The species of this 



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