

REPTILIAN REMAINS. 121 



same size and form, and are highly perfect piercing and cutting 

 instruments, with sharp and finely crenulated edges. The space be- 

 tween the fourth and fifth tooth is sufficient to contain one additional 

 tooth, and that between the sixth and seventh is sufficient for two, 

 and has in it a young tooth just appearing above the jaw. There is 

 an impression of an eighth tooth on the matrix. The whole jaw may 

 thus, when perfectly filled, have accommodated twelve teeth on each 

 side of the mouth ; in predaceous reptiles, however, the teeth are 

 often broken and are renewed, so that in adult animals they are never 

 uniform or complete. 



From the extraordinary depth of the dental bone relatively to its 

 length, and from its northern locality, Dr Leidy has named the 

 animal to which it belonged Baihygnaihus borealis. He adds : " This 

 interesting fossil is the second authentic discovery of saurian bones 

 in the New Red Sandstone of North America ; the first being those 

 found near Hossac's Creek, in Lehigh county, Pennsylvania, by Dr 

 Joel Y. Shelley, and described by my friend Mr Isaac Lea, under the 

 name of Clepsysaurus Pennsylvanicus." 



The remains of this ancient reptile must have been drifted by the 

 sea, and embedded in the sand now forming the red sandstone of 

 New London. Probably its bones, after the decay of the body, were 

 scattered over the bottom, to be buried under the next layers of sand 

 spread over it. What information can we derive from the fragment 

 which has been handed down to our time, respecting the structure 

 and habits of the creature, and the age of the rock in which it was 

 embedded? The teeth prove decisively that the animal to which 

 they belonged was fitted for capturing and devouring other animals. 

 It is difficult to imagine an instrument better fitted for cutting and 

 tearing asunder than a jaw furnished with these sharp and serrated 

 teeth. The size of the teeth, and the shortness and depth of the jaw, 

 indicate an amount of power sufficient for the destruction of large 

 animals, perhaps fishes, smaller reptiles, or even clumsy and gigantic 

 wading birds, all of which are known to have existed as far back 

 as the New Red period. Among living carnivorous reptiles, those 

 which, like the crocodile, are clumsy and less agile in their movements, 

 have elongated snouts to enable them the more easily to secure their 

 prey ; those which, like the serpents, can move with extreme rapidity, 

 have comparatively short jaws. We may therefore infer that this 

 creature was furnished with means of very rapid movement, either 

 on land or water. It could spring or dart on its prey. If we had 

 the remains of its extremities, we could determine what its means of 

 movement were, and whether the sea or the land was its sphere of 



