300 On the Sense of Feeling. 



which a small tube rises, supplied by a powerful nerve, but ceasing at the 

 surface. 



Such an organ appears to hold an intermediate place between a ' cri/pt' 

 and a ' phanera,' resembling the latter in its nervous supply and pulp, but 

 analogous to the former in their assemblage together upon certain points 

 in a conglomerate form, as well as in their external orifice. 



It has been supposed that these fishes, by such organs as these, exercise 

 the sense of touch with considerable accuracy. 



Ascending from the fishes, we arrive at the reptiles, divided into two 

 classes ; the naked and the scaly. Of the former, are the batrachians ; 

 of the latter, the ophidians or serpents, the saurians, and the chelonians, 

 or tortoises. 



The batrachians have neither a distinct epidermis, nor phanera for the 

 production of hair ; but the whole integument partakes of the character of 

 a mucous membrane, and is copiously supplied with slime by a well de- 

 veloped system of crypts. 



In these animals the cutis is dense and (with one exception) adherent, 

 as in the fishes. They possess a vascular membrane, and the pigment is 

 exceedingly brilliant. 



In the frogs proper, the skin, instead of being adherent, is attached only 

 at the extremities of the animal, so that it admits of being readily inflated 

 like a bag. It forms also, in species regularly aquatic, the interdigital 

 expansion called a web foot. 



In the proteus, siren, terrestrial and aquatic lizards, animals which have 

 been called pseudo-saurians. the cutis becomes exceedingly gelatinous, and 

 is closely adherent to the subjacent tissue. 



The tegumental diflerence between the ophidians and batrachians, and 

 the two inferior classes of reptiles, the chelonians and the saurians, consists 

 cbieflv in the scales or hard coverings with which the latter are invested ; 

 in the position of the pigment, which resides most usually upon the surface 

 of the scale itself, instead of upon the subjacent cutis ; and in the posses- 

 sion of something like nails. 



The scales of reptiles are, however, to be regarded as distinct from those 

 possessed by fishes on the one hand, and by the pangolins and some of the 

 mammalia on the other ; their solidity being entirely due to a thickening of 

 the epidermis. 



The scales of reptiles have been divided into epidermoid, dermoid, and 

 phaneric. 



Where the scaly portion is circumscribed by lines or spaces, within 

 which the epidermis is less hard and more flexible ; and where the scales 

 are flat or nearly flat plates, they are called epidermoid : where they rise 

 to a greater elevation above the skin, forming a scaly tubercle, and being 

 more immediately connected with the dermis, they are called dermoid : 

 and where they overlap one another in the inbricated manner, becoming, 



