136 



form either of a soft viscid substance as in frogs, 

 of a horny shield as in tortoises, or of scales as 

 in serpents and most lizards : some of the latter, 

 however, as the crocodile and alligator, have it 

 again in the form of hard plates, like the shields 

 of tortoises. It is of the corpus mucosum also, 

 that the claws of such reptiles as have them are 

 constituted. The proper cutis is situated under 

 this ; and as the papillae of this organ are most 

 numerous about the soles of the feet, we must 

 conceive that it is in this part principally that 

 the touch of reptiles is resident. 



The perspiration of reptiles is in general very 

 copious ; that of the salamander, for example, 

 being so much so, as to extinguish flame, and 

 thus to have given rise to the fable of its being 

 capable of living in the fire. In some, as the 

 toad, the perspired matter is of a poisonous qua- 

 lity ; and in one kind of lizard it is so acrid as to 

 blister the fingers. 



In birds, the cuticle is again membranous ; 

 while the corpus mucosum assumes the form 

 upon the mandibles, of a bill ; upon the body in 

 general, of feathers ; upon the legs, of scales ; and 

 at the extremity of the toes, of claws. Under this 

 is the cutis, which, abounding in papillee, most in 

 general, below the bill, particularly in the swan, 

 goose and duck, may be presumed to render this 

 organ the most sensible of external impressions. 



In mammiferous animals, the membranous cu- 

 ticle covers a corpus mucosum, generally of a 

 soft viscid consistence, but in some few animals 



