30 ANATOMY AND PHYSIOLOGY 



as digestive organs, are capable of supporting a 

 surprising distention, without subjecting the indi- 

 vidual to even a temporary inconvenience. In the 

 act of gorging their food, the jaws are thrown so 

 far apart, that with the organization of the spinous 

 fishes, the capsular ligaments would be torn from 

 the bones, and the blood-vessels rent from their 

 connexion with the heart. Such, indeed, is the 

 gristly elasticity of the skeleton of this second 

 natural division, that the bones are separated as 

 often as the stomach is called into vigorous action, 

 and resume their places again, without injuring, or 

 in fact, disturbing the functions of the vital or- 

 gans.* 



These grand divisions are analogous to the two 

 great classes of land animals, the one of which is 

 carnivorous, and the other is sustained by the ve- 

 getable productions of the earth. Spinous fishes 

 may be compared, in general character, to the 

 graminivorous quadrupeds, being timid, not uni- 

 versally provided with weapons of defence, and 

 possessing, to a certain extent, social habits, and 

 are therefore rarely found alone. But the cartila- 

 ginous, like the carnivorous animals, are exceed- 

 ingly voracious ; — they pursue their living ali- 



* The jaws of serpents are separated in a similar manner, in 

 swallowing food. The distortion of the Boa Constrictor, in 

 the act of gorging, is truly horrible. 



