110 FALSE-SCORPIONS 



number of times and a large number of spermatophores are thus 

 produced and received in quick succession. 



In Chelifer cancroideSy according to Vachon (1938), a nuptial 

 dance takes place during which the male vigorously displays and 

 retracts his ram's-horn organs and waves his pedipalps in the air 

 like the arms of a swimmer. The dance consists of at least three set 

 figures which are repeated rhythmically for some minutes or longer 

 if the female is unresponsive. Still dancing, he approaches his mate, 

 deposits a spermatophore and then retreats, slowly moving his 

 palps. Obedient to this signal, the female advances until she stands 

 above the spermatophore which she introduces into her sperma- 

 thecae. The male then lowers his head beneath that of his mate, 

 grips the femurs of her palps with his own claws and taps her 

 genital region with his anterior legs, thus ensuring that the sperma- 

 tozoa from the spermatophore are properly secured. 



Reproduction and life cycle 



It has been known since the time of Fabricius in 1793 that the 

 eggs of Chelifer were retained beneath the abdomen of the mother, 

 but Lubbock in 1861 was the first to observe that they were en- 

 closed in a transparent, structureless membrane attached to the 

 abdomen and that large motionless young similarly retained were 

 nourished by a milky fluid provided by the mother. Ten years later 

 Metschnikoff discovered that development involved a metamor- 

 phosis including immobile larvae which were provided anteriorly 

 with a strongly muscular sucking-apparatus and Barrois showed 

 that the larvae underwent two distinct periods of embryogenesis. 



The eggs and later the larvae may be arranged in a flat disc in 

 those species where the female continues an active existence during 

 gestation, for example in most of the Cheliferidae; but where the 

 female constructs a nest in which she seals herself up and remains 

 inactive until the development of the young is complete, they are 

 usually in a mulberry-like mass. According to Kew (1929) in these 

 false-scorpions the enormously distended females imprison them- 

 selves in brood nests where they remain hidden from view. A few 

 hours before the eggs are laid an incubation chamber or brood-sac 

 makes its appearance accompanied by peculiar muscular move- 

 ments of the mother's body. It is a delicate, transparent membrane 



