430 CLASS REPTILIA. 



as in the toads, communicates immediately with the hinder 

 mouth by a large hole, which can be perceived only in open- 

 ing simply the mouth. 



The epidermis is a kind of mucous epithelium like the 

 cuticle of the lips, or internal parts in man, which drops off 

 by shreds at several seasons of the year. 



In examining with the microscope the bed of the skin 

 covered, by the epidermis, it appears to be composed of 

 globules, which may be separated from each other, and which 

 seem to be small glands for the preparation of the bitter and 

 viscous humour which continually lubricates the surface of 

 the body in the animals in question. 



To this mucous-cutaneous tissue is owing the colours which 

 adorn the surface of the body in frogs. 



The chorion is a tissue of a very compact and dense cha- 

 racter, and, as is also the case with the toads, it is united to 

 the cellular tissue only in certain determined points ; for 

 example, at the circumference of the mouth, the middle line 

 of the body, the arm-pits, and the groins. 



From the observations of Mery we learn some curious de- 

 tails concerning the skin of the frog. This skin appears to 

 cover four cavities, separated from each other by a very thin 

 membranes, united on one side to the teguments, and on the 

 other to the muscles of the body. These four cavities cor- 

 respond to the back, the abdomen, and the sides. The skin 

 of the thigh is not attached to its muscles, except in the folds 

 of the articulations, and it forms two kinds of sacs, one before 

 and the other behind. The same thing takes place with the 

 skin of the legs. 



There is no general cuticular muscle : we merely observe 

 some fleshy fibres under the throat. These fibres descend 

 from the compass of the lower jaw, and are lost in the cel- 

 lular tissue which imites the skin to the origin of the 

 breast. 



