1660 The Zoologist— May, 1869. 



Family Vipers ( Viperida;). 

 Have no maxillary teeth in the upper jaw, but a single row of very 

 ..small palatal teeth on each side of the palate, and in addition to them 

 there is articulated to each ramus of the upper jaw a small but distinct 

 supplementary bone, which bears an elongate and curved tubular 

 poison-tooth or fang. There is no pit or depression on the side of 

 the face, as in the family of Rattle-Snakes [CrotalidcB). We have but 

 one British species, 



The Viper {Pelias Berus). 



Common Viper, Adder, Common Adder ; varieties as regards colour 

 are also called Red Viper, Blue-bellied Viper, Black Viper, Chersea 

 Viper. 



The Viper being the only British representative of the family 

 Viperidae, a considerable amount of repetition becomes necessary in 

 compiling the description, since the characters of the species must of 

 neces.sily be those of the family. The head is flattened on the crown, 

 and considerably dilated behind the eyes : the gape extends the 

 entire length of the head. I have found no teeth inserted in the 

 maxillaiy bones of the upper jaw, but there is a single row of very 

 small sharp-pointed teeth on each side of the palate ; and also a single 

 series of ten or twelve teeth, sharp-pointed and bent backwards to- 

 wards the throat, on each side of the lower jaw. In addition to these 

 there is a single tubular tooth, or poison-fang, on each side of the 

 upper jaw : this is not absolutely fixed in the maxillary bone itself, 

 but in a small separate or supplementary bone which is articulated to 

 the maxillary bone, and the muscles attached to it are so formed and 

 arranged that the fang, at the will of the animal, can either be pro- 

 jected at a right angle with the maxillary bone, or entirely concealed 

 among the folds of integument within the mouth. The neck is 

 manifestly restricted, but scarcely so much so as in the Common 

 Snake ; the body gradually increases in size to the middle, and is of 

 nearly uniform diameter thence to the vent, from which point it 

 rapidly and rather suddenly tapers, and terminates in a pointed tail : 

 the dorsal and lateral scutes are keeled, and form eighteen longitudinal 

 series. The ventral scutes vary in number : in five specimens, 

 counted with the greatest possible care, there were found to be respec- 

 tively 146, 148, 156, 156 and 178 j the numbers of subcaudal scutes 



