84 INTRODUCTION 



more active during the breeding season. A Viper- 

 catcher in France is said to obtain good results by 

 rubbing his boots with these glands, as a means of 

 attracting the snakes in the spring. 



In European species pairing takes place in spring, 

 sometimes again at the end of summer or in 

 autumn. After hibernation the testes of the males 

 are rather voluminous, and the sperm-ducts are often 

 full of spermatozoa. The male gets alongside the 

 female, sometimes seizing her round the neck with 

 his jaws, and remains stretched out against her or 

 twists the posterior part of his body in a few coils 

 around hers. In the Vipers the bodies of the pairing 

 individuals are completely entwined. The male 

 then endeavours to bring the two anal orifices 

 together, and when he has succeeded in getting the 

 female to distend her cloacal opening, the intro- 

 mittent organs are suddenly everted into the vagina. 

 The union of the sexes sometimes lasts only a few 

 minutes, but usually an hour or more; it has even 

 been observed to last a whole day. Several copula- 

 tions may take place at intervals of a few days. 

 Many snakes are gregarious during the breeding 

 season, and great numbers of males have been seen 

 wriggling round the females, forming with their 

 coils huge lumps or an entangled mass like a ball. 

 The more or less prehensile tail with which 

 thoroughly aquatic snakes, such as Hydrophis and 

 Acrochordus, are provided, is no doubt of use in 



