470 WOUNDS. 



Ly prominent overhanging rugose plates ; the pupil is elongated 

 and vertical ; the upper lip descends on either side, like that of 

 a mastiff, so as to conceal the poison-fangs ; the scales are in 

 almost every instance keel-shaped (carinated), or sharp-pointed 

 (muricated). Closer examination of the internal structures of 

 the head and oral organs will still further disclose the more 

 decisive characters of the viperina. The maxillary bones are 

 exceedingly short and mobile, and each supports a single long- 

 pointed and recurved tooth, termed the poison tooth or fang, 

 perforated throughout its entire length by a slender canal. 



By a peculiar arrangement of the maxillary bones and muscles, 

 this tooth, when not in action, can be reclined into a groove in the 

 gum, where it lies completely concealed ; but it can be suddenly 

 and forcibly erected when the viper is preparing to strike its 

 deadly blow. The rest of the bones connected with the jaws, 

 face, and gullet are also very loosely articulated, and so disposed 

 as to admit of enormous dilatations of the mouth and entrance 

 into the pharynx. Besides the fangs, the upper jaw contains no 

 teeth ; but a series of pointed recurved solid teeth are arranged 

 along the palate. In the lower jaw similar teeth are found at 

 the extremity. 



The fang is traversed by a narrow canal, continuous above, 

 with a pouch or sacculus surrounding the base of the tooth, into 

 which opens the long curved duct of the poison gland. This 

 organ, wliich, with various modifications, may be described as 

 composed of tubular follicles communicating with a common 

 canal, has a thick aj^oneurotic wall surrounded by muscular 

 fibres, in most cases apparently connected with the temporalis 

 muscle, and which are su]3posed to act as compressors of the 

 gland and ejaculators of its contents. The poison gland is 

 usually below and a little behind the orbit ; but in one remark- 

 able instance, catcsus rJiombeatus, it is of an enormous size, and 

 situated on the back, extending from the nape of the neck 

 through nearly one-sixth of the entire length of the body, lying 

 immediately beneath the integument, and superficial to the ribs 

 and costal muscles. 



The venom of serpents when fresh is a transparent yellowish 

 or greenish viscous neutral fluid, very much resembling saliva ; 

 insipid and almost inodorous ; heavier than water, and not very 

 readily mixable with it; the mixture when shaken becoming 



