6Q VIPERID.E. 



specimens are regularly formed and symmetrically placed ; 

 but in others tliey are very irregular. There are three Avhich 

 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 hun- 

 dred 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. I have 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 some, with lighter or darker 

 spots, in others almost wholly black. 



The tendency of this species to vary in its colours has 

 occasioned an erroneous multiplication of species by various 

 authors. Some of the more remarkable and conspicuous 

 varieties I proceed to describe. 



