OF THE INTEGUMENTS. 69 



OP THE INTEGUMENTS. 



The general integuments of Ophidians, intended to resist 

 the influence of the elements and of external mechanical 

 causes, form a very thick cuirasse, which invests the whole 

 body of the animal, and is fortified by an epidermis, very 

 hard and corneous. That it may obey the movements of 

 the animal and the extension of parts by which the enlarge- 

 ment of the volume of the body is produced, it was neces- 

 sary for that skin to be divided into a great number of 

 compartments, separated by intervals, so that from this 

 construction should result as many articulations susceptible 

 of separation and approximation to each other. The pro- 

 jecting compartments, denominated scales when they are 

 small, plates or shields when they are large, are formed by 

 layers of integuments, much thicker than in the intervals, 

 which present a skin of a more delicate organization, much 

 contracted when the animal is in a state of repose, &c., 

 covered with an epidermis extremely thin, a little trans- 

 parent, and soft. It is obvious that these interstices are 

 only apparent to the eye when the body of the animal is 

 dilated ; concealed almost constantly by the edges of the 

 scales, and deprived of light, they are always of a white 

 colour ; and it is only in some species of Tropidonotus that 

 the mucous tissue of those parts is tinted of a beautiful 

 vermilion on the region of the heart. It is not so with 

 that part of the mucous tissue which enters into the forma- 

 tion of the scales, which often shine with all the splendour 

 of the rainbow, a brilliancy more or less vivid according 

 to the nature of the horny and transparent epidermis with 

 which the scales are covered. This is the reason why some 

 serpents, and especially those of the genus Dendrophis, 

 present a very uniform system of colour, although their 

 mucous tissue be ornamented with the most beautiful tints. 

 It is equally evident, that the tints of serpents should 

 change about the time of casting their sloughs, when the 

 epidermis is tarnished as it insensibly detaches itself from 

 the inferior layers of the skin. Then only permitting the 

 rays of light to pass imperfectly, it reflects them in a man- 



