OS VIPERA BERUS. 



tory duct to the cavity of the tooth which communicates with that 

 of the sac, and terminates near the tip in a small aperture, by which 

 the poison is expelled into the wound made by the tooth. The 

 poisonous fluid is propelled into the hollow of the curved fang by 

 a small constrictor muscle, which, however, never expels at once 

 the whole of the contents of the sac. 



As this species is subject to great differences in colour, depend- 

 ing on age, sex, or climate, it has been multiplied into the follow- 

 ing species, which Dr. Leach, in the third volume of his Zoo- 

 logical Miscellany, has reduced to the rank of varieties : 



1. Black Viper, Coluber Prester, Lin. Sysl. Nat. i. 377. 

 Colour nearly black. 



'2. Blue-bellied Viper, Rev. Revett Shcppard, Lin. Trans, vii. 

 p. 56. In this the back is more tinged with brown than usual, 

 and the belly is of a rich shining blucish-black colour, somewhat 

 resembling that of polished steel. 



3. Red Viper, Rev. Thos. Racket, Lin. Trans.xu. p. 349. This 

 is supposed to be the Coluber Chersea, of Linneus. Above, it is 

 of a bright red colour, and is characterized by a heart-shaped mark 

 on the head, and a dark spot near the extremity of the tail. It is 

 extremely rare in this country, but has been found on Cranbornc 

 Chase, in Dorsetshire, where it is known to the gamekeepers under 

 the name of " red viper." It has likewise been found by the Rev. 

 Revett Shcppard, in the parish of Levington, and other places in 

 the county of Suffolk, in arid waste situations. 



The two varieties figured on the accompanying plate were taken 

 in the neighbourhood of Harrow on the Hill, near London, last 

 autumn. 



This reptile is viviparous, pairing in May, and producing from 

 twelve to twenty-five young at a birth, towards the close of sum- 

 mer. It feeds on insects, lizards, frogs, and mice. It retires into 

 holes in the earth, where it becomes torpid during winter, and, 

 like all other snakes, can support, without any material suffering, 

 a fast of many months. 



The poison of the Viper is a yellow liquid, inodorous, insipid, 

 and when applied to the tongue occasions numbness. It has the 

 appearance of oil, before the microscope, but it unites readily with 



