SCORPIONS 83 



At length the male either digs a hole without entirely quitting 

 its hold of the female, or else leads her to a suitable retreat into 

 which both disappear. True copulation takes place, which is rare 

 in the Arachnida. In the course of this act the male protrudes cer- 

 tain special organs already referred to and these form a temporary 

 penis with which he inserts the sperm and finally places in position 

 a vaginal plug — a kind of postnuptial hymen (Vachon, 1953). 

 Afterwards the female not infrequently eats him. 



In the South African Opisthopthalmus latimanus the classical 

 'arbre droit' is either absent or only fleetingly present, while the 

 'promenade a deux' does not usually last longer than an hour. The 

 male holds the chelicerae of the female and not, as in other species, 

 her pedipalps. The promenade takes place in a limited area and if 

 the ground is rough the male clears the soil particles from the 

 space in which the pair are dancing. Shortly after the start, the 

 genital opercula of the female opens and a little later that of the 

 male also opens as the extrusion of a spermatophore begins. As 

 soon as this is clear of the genital aperture of the male he moves 

 back slightly so that it lies freely on the ground. He then jerks the 

 female violently, drawing her over the spermatophore and half 

 lifting her at the same time. She lowers her body over the capsule 

 of the spermatophore, which becomes inserted in her genital aper- 

 ture. 



Thus in O. latimanus there is no true copulation but a fertilisa- 

 tion mechanism similar to that found in false-scorpions. The 'pro- 

 menade a deux' results in the female being jerked back and forth 

 until she is in the correct position over the spermatophore which 

 she then picks up (Alexander, 1956).t 



Reproduction and life cycle 



The fertilised eggs develop inside the mother and the young are 

 born alive. The course of development varies according to whether 

 the eggs are rich in yolk, as in the Buthidae, or lacking in yolk, as 



t Since this account was written, similar information has been ob- 

 tained on the mating habits of the Chactidae, Bothriuridae and Buthidae 

 as well as the Scorpionidae. It therefore seems likely that insemination by 

 means of spermatophores occurs throughout the order and that true 

 copulation may not take place as previously supposed (Alexander, 1957). 



