248 BRITISH SERPENTS. 



men was sent to me by the Eev. C. Davies, Cenarth, 

 Caermarthenshire, for identification. It turned out to 

 be a variety of the adder known as the " black adder " 

 (the Coluber prester of some writings). This specimen 

 was a female 20J inches long, and is the first recorded 

 in this part of the country. Still more interesting 

 is the fact, which I have since ascertained, that the 

 black adder is not uncommon in the neighbourhood of 

 Cenarth, though but rarely killed on account of the 

 great dread the inhabitants have of its danger. There 

 are two specimens in the South Kensington Museum 

 taken in this country, and a considerable number from 

 the island of Seeland, where they seem fairly common. 

 G. A. Boulenger has given special attention to the pro- 

 duction of the melanism which he described in the 

 'Zoologist' of February 1895. He has shown that the 

 black colour is produced differently in the two sexes : 

 in the males by the expansion of the black markings, 

 in the females by " a gradual darkening of the ground 

 colour." 



VII. North Wales Province. 



Vipera herns. — The distribution in this province is 

 very irregular, common in some places, in others the 

 adder is apparently absent. 



Tropidonotus natrix. — This species is generally dis- 

 tributed in North Wales, in some places growing to a 

 large average size. 



