70 VIPERAD A. 
palatine bone on each side. Neck rather smaller than the 
back of the head, from which the body increases to nearly 
the middle of the entire length; the rest of the body to 
the vent scarcely diminishing; the tail becoming almost 
abruptly smaller, and tapering to its extremity, which is 
pointed; the tail varies in its proportion to the body, but 
is generally not more than one-eighth of the total length, 
and in some even less. The head is covered with small 
squamous plates, which in some specimens are regularly 
formed and symmetrically placed; but in others they are 
very irregular. There are three which are larger than the 
others,—namely, the vertical, and the pair of occipital 
plates. The scales of the back and sides are semi-oval, or 
somewhat lanceolate, imbricated, and distinctly carinated ; 
they are disposed in eighteen series. The plates of the 
abdomen have nothing particular in their form; they vary 
in number, but usually consist of about one hundred and 
forty to one hundred and fifty, and those of the’ tail are 
about thirty-five pairs. 
The general ground-colour varies considerably. In 
some it is nearly olive, in others a rich deep brown, and in 
others a dirty brownish yellow; and when in high health, 
and shortly after having cast the skin, the surface is 
slightly iridescent in particular lights. A mark between 
the eyes, a spot on each side the hinder part of the head, 
and a zigzag line running the whole length of the body 
and tail, formed by a series of confluent rhombs, as well as 
a row of small irregular triangular spots on each side, all 
of a much darker hue than the ground-colour of the body, 
and frequently almost black. Ihave a specimen in my 
collection which I received alive from Hornsey Wood, the 
ground of which was almost perfectly white, and all the 
markings jet black. The under parts are plumbeous in 
