178 CLASS REPTILIA. 



banks of rivers in the torrid zone, where the sun is scarcely 

 ever veiled by clouds, and where the luminous rays are 

 incessantly and intensely reflected by the waves and the 

 sands, a strength of this organ was peculiarly indispensable 

 to these animals, to prevent their eyes from being injured 

 and speedily destroyed by the excessive action of light to 

 which they are perpetually subjected. 



Like other reptiles the saurians have an auditory organ 

 composed of a vestibulary sac, a vestige of cochlea, and 

 three semi-circular. But the crocodile alone has any ap- 

 pearance of an external meatus auditorius, because the skin 

 forms a kind of thick cover above the tympanum. This 

 serves to explain a passage in Herodotus, who tells us that 

 the Egyptians were in the habit of suspending jewels in the 

 ears of the crocodile. The osseous labyrinth presses closely 

 on the membranaceous, investing it throughout with a thin 

 and hard lamina. The auditory apparatus of these animals 

 is altogether very imperfect, and we may conclude that their 

 powers of hearing are equally so. This conjecture is 

 strengthened by the fact that they are either dumb, or only 

 emit hoarse, confused, and disagreeable sounds. Their 

 olfactory organs are still more imperfect, and the sense of 

 taste is in all probability less developed than even that of 

 smell. The tongue, in fact, of the greater number of sau- 

 rians, though singularly extensible and mobile, is terminated 

 by two long points which are semi-cartilaginous and cor- 

 neous, and though it is soft and humid, its surface is smooth. 

 In the crocodiles it is so fixed by the edges and point that it 

 seems to be wanting, and was always thought to be so by 

 the ancients. 



Nor can the sense of touch be supposed to give rise to 

 any great number of distinct impressions in these animals, 

 covered as they are with hard scales, or a corneous epider- 

 mis. This skin falls at least once every year in the spring- 



