WHIP-SCORPIONS AND OTHERS 129 



non-segmented carapace at the front edge of which is a mobile 

 hood or cucullus which fits down tightly over the chelicerae. No 

 true eyes are present, but vague pale spots on each side of the cara- 

 pace may well represent vestigial eyes. The pedipalps are of six 

 segments and are remarkable in that their coxal segments are fused 

 in the mid-line: they are chelate as are the two-segmented cheli- 

 cerae. The prosoma is joined to the opisthosoma by a narrow 

 pedicel, but this is hidden from view by expansions of the base of 

 the abdomen w^hich fits very closely against the prosoma, the 

 juncture forming a coupling device. The living animal is able to 

 disengage the carapace from the abdomen so that the genital 

 orifice is exposed during mating and oviposition. The opisthosoma is 

 composed of nine segments of which only the first four are well 

 defined, while the last three form a small pygidium. The legs are 

 short and stout, the third pair being modified as copulatory organs 

 in mature males, a character otherwise found only in certain mites. 



The order is limited to a single family, the Ricinoididae (or 

 Cryptostemmidae) and contains only two genera, Ricinoides and 

 Cryptocellus. Of these the first is represented by six West African 

 species, the second by seven species having a distribution from 

 Texas to the Amazon basin. After the discovery in 1838, of the 

 first specimens of these very rare animals, only 32 were found 

 until, nearly a century later in the British Cameroons no less than 

 317 specimens oi Ricinoides sjostedti were obtained. It is not en- 

 tirely surprising, therefore, that the biology of these peculiar 

 creatures is practically unknown, although specimens have been 

 kept alive at the British Museum (Natural History) for over a year 

 (Fmnegan, 1935). 



Ricinulei appear generally to live under damp, fallen leaves in 

 equatorial forests. Certain Mexican species are cavernicolous and 

 specimens of Cryptocellus dorotheae have been found shortly after 

 rains in the sandy soil of the Rio Grande River Valley. They were 

 taken from under slabs of concrete, heavy sheet iron and roofing 

 material which had not been disturbed for several years. The 

 creatures are very sluggish and have a slow and curious gait. 

 They move with considerable deliberation and seem to feel their 

 way along with their front pair of legs, their movements resem- 

 bling those of a tick crawling over the ground. Sudden illumin- 



I S.S.C.M. 



