Palaeozoic Arachnida of North America. 25 



Turning now our attention to the other orders represented both 

 in the Carboniferous and recent faunas, we must first of all exclude 

 from consideration the few very inadequately known forms of Opili- 

 ones. The presence of maxillary lobes in the coxae of recent Opili- 

 ones would speak for an old origin of this order, but for some reason 

 it is very poorly represented in the Carboniferous fauna, if indeed 

 the species described under it belongs to it The order Ricinulei 

 is at present entirely confined to Africa and Brazil, but is represented 

 in the Carboniferous of both Europe and North America. The car- 

 boniferous genus Polyochera belongs apparently to the rcent family 

 Crypt ostemmidae. One species is known from Europe and 2 from 

 Mazon Creek. The genus Curculioides belongs to the extinct family 

 Holotergidae, which represents a further development inasmuch as 

 the separate tergites are fused into one shield. It is represented by 

 a single species in Europe and 2 species in North America. The order 

 Solifugae is at present represented mainly in tropical and hot coun- 

 tries, but some species occur in the southern United States, going as 

 far north as Kansas, and some in South Russia and southern Europe 

 (Greece, Spain). The only Carboniferous species of this order is 

 from North America. The order Araneae or spiders is, perhaps with 

 the exception of the Acari, the richest among recent Arachnida. Of 

 its three sub-orders, the Arachnomorphae are spread all over the 

 world. The Theraphosae or Mygalomorphae, including all "taran- 

 tulas" and trap-door spiders, are preeminently tropical, but some 

 species occur a? far north as southern France in Europe and the Dis- 

 trict of Columbia in this country. The third suborder, or Mesothelae, 

 is almost wholly extinct. Only 2 recent species are known from 

 Pinang and Sumatra. This was the best represented sub-order 

 among the spiders of the Carboniferous period. It was much better 

 represented in Europe than here ; we have only i genus with 2 species, 

 whereas 5 genera containing 5 species have been decsribed from Europe 

 and 6 more European species have been probably incorrectly placed 

 under the American genus Arfhrolycosa. No remains of the Mygalo- 

 morphae are known either from Europe or from North America. 

 Of the Arachnomorphae 3 species belonging to as many genera have 

 been described from Europe, but no representatives of this sub-order 

 have been found in North America, although the recent North 

 American spider fauna is richer than the European one. The order 

 Pedipalpi is at present restricted to hot and tropical countries. It is 

 totally absent in Europe, while i species of a whip scorpion and 2 spe- 

 cies of the sub-order Amblypygi are found in Texas, Florida, Arizona 

 and California. The sub-order Uropygi or whip scorpions are re- 



