A CHAT WITH TROF. COPE — CONTINUED. 345 



the lower jaw. Instead of this each half of that jaw 

 was articulated or jointed at a point nearly midway 

 between the ear and the chin. This was of the ball 

 and socket type, and enabled the jaw to make an 

 angle outward, and so widen, by much, the space 

 inclosed between it an its fellow. The arrangement 

 may be easily imitated by directing the arms for- 

 ward, with the elbows turned outward and the 

 hands placed near together. The ends of these bones 

 M'ere in the Pythonomorphs as independent as in the 

 serpents, being only bound by flexible ligaments. 

 By turning the elbows outward, and bending them, 

 the space between the arms becomes diamond-shaped, 

 and represents exactly the expansion seen in these 

 reptiles, to permit the passage of a large fish or other 

 body. The arms, too, will represent the size of jaws 

 attained by some of the smaller species. The out- 

 ward movement of the basal half of the jaw necessa- 

 rily twists in the same direction the column-like bone 

 to which it is suspended. The peculiar shape of the 

 joint by which the last bone is attached to the skull, 

 depends on the degree of twist to be permitted, and, 

 therefore, to the degree of expansion of which the 

 jaws were capable. As this differs much in the dif- 

 ferent species, they are readily distinguished by 

 the column or "quadrate" bone when found. 

 There are some curious consequences of this struct- 

 ure, and they are here explained as an instance 

 of the mode of reconstruction of extinct animals 

 from slight materials. The habit of swallowing large 

 bodies between the branches of the under-jaw ne- 

 cessitates the prolongation forward of the mouth 

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