VIPERA 239 



Reproduction. — Pairing takes place in April and 

 May, and the young, five to twenty in number, are 

 born in August or September, exceptionally as early 

 as the end of July ; the young, on releasing them- 

 selves from the thin, transparent membrane in which 

 they are enclosed at birth, measure 6 to 8 inches. 

 According to J. Geithe, a black female from Saxony 

 gave birth to seventeen young, of which only one, a 

 male, was black. 



It is probable that exceptionally some individuals 

 pair late in the summer or in the autumn. There is 

 a trustworthy record, by Eiffe, of three pregnant 

 females having been caught near Hamburg on 

 March 12, 1882, one of them giving birth to young 

 on the following day. 



Dicephalous young have occasionally been observed. 

 One 6 inches long was found crawling in a field near 

 Hornburg in Germany in October, 1895, and, having 

 been kept alive for some time, was observed to hiss 

 and open the two mouths alternately when taking 

 up a defensive attitude. Another similar monster, 

 from Cornwall, is reported to have been sent alive to 

 the London Zoological Gardens in 1854. 



24. Vipera aspis, Linnaeus 

 The Asp Viper 



Form. — Rather more elongate than in the preced- 

 ing. Snout flat above, more or less distinctly turned 

 up at the end, with sharp, not or but very slightly 



