OF THE INTEOUMENTS. 
G9 
OF THE IlfTEOUMENTS. 
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- 
