428 



ARACHNIDA SOLIFUGAE 



The nervous system, notwithstanding the fact that the three 

 last thoracic segments are free, is chiefly concentrated into a 



L cfi- 



ch£ 



segments 



mass surrounding the oesophagus. Nerves 

 are given off in front to the eyes, the 

 labrum, and the chelicerae, while double 

 nerves radiate to the pedipalps and to 

 the legs. From behind the nerve-mass 

 three nerves emerge, and pass through 

 the diaphragm to enter the abdomen. The 

 median nerve swells into an " abdominal 

 ganglion " just behind the diaphragm, and 

 is then distributed to the diverticula of 

 the alimentary canal. The lateral nerves 

 innervate the generative organs. 



The respiratory system consists of a 

 connected network of tracheae communi- 

 cating with the exterior by the stigmata, 

 whose position has already been described. 

 There are two main lateral trunks extend- 

 ing nearly the whole length of the body, and 

 giving off numerous ramifications, the most 

 important of which are in the cephalo- 

 thorax, and supply the muscles of the 

 chelicerae and of the other appendages. 

 The generative glands do not essen- 

 tially differ from the usual Arachnid type, though the paired 

 ovaries do not fuse to form a ring. There are no external 

 organs, and the sexes can only be distinguished by secondary 

 characteristics, such as the " flagellum " already mentioned. 



Classification. — There are about a hundred and seventy 

 species of Solifugae inhabiting the warm regions of the earth. 

 No member of the group is found in England, or in any except 

 the most southern portions of Europe. 



Kraepelin ^ has divided the group into three families — Galeo- 

 didae, Solpugidae, and Hexisopodidae. 



Fam. 1. Galeodidae. — The Galeodidae have a lancet-shaped 

 flagellum, directed backwards. There is a characteristic five-toothed 

 plate or comb covering the abdominal stigmata. The tarsus of the 

 fourth leg is three-jointed, and the terminal claws are hairy. 



' Das Tierreich, Berlin, 12. Lief., Arachnoidea, 1901, p. 4. 



abd.g: 



Fig. 218. — Nervous .system 

 of Gahodes. cibd.g, Ab- 

 dominal ganglion ; ch, 

 cheliceral nerve ; ch.f, 

 chitinous fold ; ch.r, chitin- 

 ous rod ; g.n^ generative 

 nerve ; I, labial nerve ; 

 st, position of stigma. 

 (After Bernard.) 



