On the Sense of Feeling. 301 



in fact, scales in the usual acceptation of the term, they are called /jAaweric- 

 — a bad term, for they are not secreted by phanera at all. The figure and 

 structure of these scales and plates form, as in the fishes, grounds for 

 zoological distinctions. 



At certain periods, scaly reptiles cast their epidermoid covering, not as 

 in man and the mammalia, piece-meal, but at once, so that the animal steps 

 out of his skin, as out of a sheath, leaving a correct mould of himself be- 

 hind him. So complete is this shifting, that even the outer layer of the 

 cornea has been found with the skin. After this process, the colours of 

 the new skin are, of course, for a time more vivid and brilliant, and this is 

 peculiarly the case with the snake. 



Of the scaly reptiles, the serpents possess an integument of considerable 

 strength, not very sensitive. The cutis of many of them, as the Boa, is 

 highly elastic, especially about the neck. 



The Lizards are protected by scales, more or less imbricated ; and in 

 those in whom the feet are not at all, or but imperfectly, developed, the 

 integument is very dense, and the scales of the dermoid description. The 

 feet of the higher classes of lizards are furnished with nails, and their 

 brilliant colours are said to depend upon the solar rays. 



In the Iguanas the integument is thick, especially about the tail. The 

 scales are dermoid, but not imbricated ; and their colours often brilliant. 

 They have a strong sharp nail upon each digit, and are said to be the 

 highest animals in whom are found the 'femoral pores.' These are perfo- 

 rations, determinate in number in each species, one of which passes through 

 each scale, near the inside of the thigh, being the excretory of a small 

 crypt below. 



In the Agamas, the skin is thinner ; and the great development of the 

 vascular tissue in these animals, and more especially in the cameleons, will 

 explain in some degree the singular property which they possess, of 

 changing their colour. 



In the Geckos, the integument is tolerably soft and mucous ; they have 

 a nail upon each digit, but upon that corresponding to the thumb, it is so 

 small as frequently to have been overlooked. 



In the Crocodiles, the skin is adherent in a very remarkable degree, es- 

 pecially about the cranium, where it seems almost to form parcel of the 

 bone. It is thick and hard upon the back, capable of turning a musket 

 bullet; rather less so upon the belly and flanks ; and materially thinner at 

 the flexures of the joints, and upon the interdigital expansions. 



The epidermis of the crocodile forms those broad rectangular plates, 

 which cover the lower part of the animal from one extremity to the other, 

 and which, meeting along the back, form a rigid crest. 



The nails are small, and do not exist upon the outer digits. 



The tortoises and turtles, the highest of the class reptiles, are remark- 

 able for the extreme beauty of their case. In these animals the cutis is 



No. 5.— Vol. I. 2 R 



