388 ARACHNIDA ARANEAE chap. 



terricolous, but inhabit trees, either boring holes in the bark, 

 or constructing a sort of silken retreat fortified by particles 

 of wood. 



(iv.) The Ctenizinae form a large group, including some 

 forty genera. All the " Trap-door " Spiders of the Continent fall 

 under this sub-family, which, moreover, has representatives in all 

 the tropical and sub-tropical regions of the world. A rastellus is 

 always present, and the eyes form a compact group on an emin- 

 ence. The coxae of the pedipalps are longer than in the groups 

 previously mentioned, and there is no production of the internal 

 angle. The laliium is generally free. 



The commonest European genus is JVemesia, of which about 

 thirty species inhabit the Mediterranean region. The cephalo- 

 thorax is rather flat, and the central fovea is recurved (^-^). 

 The burrow is sometimes simple and sometimes branched, and 

 the trap-door may be either thin, or thick with bevelled edges. 



Allied genera are Hermacha and Racliias in South America, 

 Spiroctenus in South Africa, Genysa in Madagascar, Scalidognathus 

 in Ceylon, and Arhanitis in New Zealand. The genus Cteniza 

 (fovea procurved ^^) possesses only a single species {C. sauvagei), 

 found in South -East France and Italy. 



Pachylomerus is a widely-distributed genus, being represented 

 in North and South America, Japan, and North Africa. The 

 tibiae of the third pair of legs are marked above by a deep 

 impression near the base. A closely allied genus, Conothele, 

 inhabits Southern Asia and New Guinea. 



The widely-distributed genus Acanthodon, which has repre- 

 sentatives in all the sub-tropical countries of the world, together 

 with the South American genera Idiops and Pseudidiops, and the 

 Indian genus Heligmonerus, present a peculiar arrangement of the 

 eyes, one pair being situated close together in the middle of the 

 front of the caput, while the remaining six form a more or less 

 compact group some distance behind them. 



Among the many other genera of the Ctenizinae may be 

 mentioned Cyrtcmchenms, of which many species iuhal)it North- 

 West Africa, and its close ally Amhlyocarenum, represented on both 

 shores of the Mediterranean, and in North and South America. 

 They differ from Cteniza chiefly in the possession of strong scopulae 

 on the tarsi and metatarsi of the first pair of legs, and in the 

 double row of teeth with which the tarsal claws are furnished. 



