AND THEIR FUNCTIONS. 121 



seizing and gripping prey, but Nature has provided the 

 crocodile with a mouth of such a kind as to compensate for 

 this defect. A downward blow, he says, is more powerful 

 than one delivered upwards, and so also a downward motion 

 of the upper jaw is more effective for seizing and holding 

 prey than an upward movement of the lower jaw.* The 

 fact that the crocodile s lower jaw is moved is liable to 

 escape notice chiefly because it extends some distance behind 

 the head. 



In the neck of the lion and of the wolf, Aristotle says, 

 there is, for the sake of strength, only one bone.t These 

 passages have been specially cited by some writers to show 

 that Aristotle made anatomical observations carelessly. It 

 would be more correct to say that, with respect to the 

 passages referred to, he made no anatomical observations at 

 all, but merely expressed a popular belief. 



Aristotle gives but little information about the backbone 

 of animals. To account for the great mobility of snakes, he 

 says that their vertebrae are cartilaginous and easily bent. I 

 The vertebrae of snakes are made of hard bone, and they 

 are numerous and loosely connected by means of ball-and- 

 socket joints. For these reasons the backbones of snakes 

 are ivery flexible. It is very probable that Aristotle never 

 examined the skeleton of a snake, for, in another passage, 

 he says that a snake has thirty ribs. Further, his state 

 ments about the backbones of snakes are not consistent, for, 

 in H. A. i\i. c. 7, s. 7, he says that they have a spinous back 

 bone, like that of a fish. 



Speaking of the chamselcon, he says that its ribs, which 

 unite together, extend downwards towards the middle line 

 of its abdomen, as in fishes.!]. 



Except when agitated and puffed out with air, the 

 chamaeleon has deep sides and a laterally compressed body, 

 not unlike that of many fishes. Numerous thin ribs run 

 down to the sternum, and, behind these, some pairs of long 

 and very thin ribs meet ventrally and form a series of hoops. 

 The chamseleon is one of the animals with which Aristotle 

 was well acquainted, and it is practically certain that he 

 dissected it. 



Aristotle says that, in the flat cartilaginous fishes, there 

 is, in the position of the vertebral column, a cartilage taking 



# P. A. iv. c. 11, 6916. \ H.A. ii. c. 1, s. 1 ; P. A. iv. c. 10, 68Ga. 

 | P. A. iv. c. 11, 692a. H. A. ii. c. 12, s. 12. 

 II Ibid. ii. c. 7, s. 1. 



