iv. II. 127 



In some oviparous quadrupeds, namely in lizards, the tongue 

 is bifid, as also it is in serpents, and its terminal divisions 

 are of hair-like fineness, as has already been* described.^'' 

 (Seals also have a forked tongue.) This it is which accounts 

 for all these animals being so fond of dainty food.'^ The teeth 

 in these oviparous quadrupeds are of the sharp interfitting kind, 

 as also are the teeth of fishes.*^ The organs of all the senses 

 are present; and these resemble those of other animals! Thus 

 there are nostrils for smell, eyes for vision, and ears for hearing. 

 The latter organs, however, do not project from the sides of 

 the head, but consist simply of the duct, as also is- the case in 

 birds. This is due in both cases to the hardness ^^ of the 

 integument ; birds having their bodies covered with feathers, 

 and these oviparous quadrupeds with horny plates. These 

 plates are equivalent to scales, but of a harder character. This 

 is very manifest in tortoises and river crocodiles, and also in 

 the large serpents: For so hard are they in these animals, as 

 to become even stronger than the bones.^* * . 



These animals have no upper eyelid, but close the eye with the 

 lower lid.'^ In this they resemble birds, and the reason of the 

 peculiarity, is the same as was assigned in their case.^^ Among 

 birds there are some that can not only thus close the eye, but 

 can also blink by means of a membrane which comes from its 

 inner corner. But none of the oviparous quadrupeds blink in this 

 manner." For their eyes are harder than those of birds.^^ The 

 reason for this is that sharpsightedness is of very considerable 

 service to birds, flying as they do in the air, whereas it would be 

 of comparatively small use to the oviparous qiiadrupeds, seeing 

 that they all live in holes. 



Of the two separate portions which constitute the head, namely 

 the upper part and the lower jaw, the latter in man and in the 

 viviparous quadrupeds moves not only upwards and downwards, 

 but also from side to side ; ^^ while in fishes, and birds, and 

 oviparous quadrupeds, the only movement is up and down. The 

 reason is that this latter movement is the one required in biting 

 and dividing food, while the lateral movement serves to reduce 

 substances to a pulp. To such animals, therefore, as have grinder- 

 teeth this lateral motion is of service ; but to those animals that 

 have no grinders it would be quite useless, and they are therefore 

 invariably without it. For nature never makes anything that is 

 691b. . 



