SUBCLASS II 



EMBOLOBRANCHIATA 



789 



the solitary genus Kustarachne Scudder (Fig. 1516), of wliicli three Carboniferous 

 species have been described. Chelicerae not observed ; pedipalpi chelate, their 

 coxae fused solidly together ; ab- 

 domen segmented, pediculate, the 

 terminal segment annuliform ; legs 

 long and slender. 



The order Solpugida (Solifugae) 

 has the head fused with the first 

 thoracic segment, all the remaining 

 thoracic segments being free. Cheli- 

 cerae chelate : pedipalpi pediform ; 

 abdomen segmented ; respiration by 

 means of tracheae ; trochanters two- 

 jointed ; coxae and trochanters of 

 the fourth pair of legs with a row 

 of characteristic " maleoli." Proto- 

 solpiiga Petrunk. (Fig. 1517) is 

 known from the 



Fig. 1516. 



Fi<^ lai; 



r roti.isolpuga carhonaria Pet- 

 runk. Coal Measures ; Mazou 

 Creek, Illinois, i/i (after Pet- 

 runkevitch). 



Kiistanichne tenuipes 



Carboniferous. Scudder. Coal Measures; 



,, , „ 1 i • 1 Mazon Creek, Illinois. 



Modern forms are sulitropical. 3/.,(afterPetrunkevitch). 



The order Ricinulei or Podo- 

 (jonida, is represented in the'^nodern fauna by two tropical genera, and includes also 

 a few Carboniferous forms. Head and thorax fused, forming a cephalothorax, in 

 front of which is 'a movable plate called the " cucullus." Abdomen composed of 

 nine segments, but so , united with the cephalothorax that the first and second 

 abdominal segments are not visible. The three hindmost segments are small, annular, 



forming a short " tail." 

 Chelicerae are two- 

 jointed, chelate; pedi- 

 palpi chelate ; tro- 

 chanter of first and 

 second pairs of legs 

 two-jointed ; the third 

 pair of legs in the 

 male is modified as a 

 copulatory apparatus ; 

 eyes absent in both 

 sexes. Polyochera 

 Scudder (Fig. 1518); 

 and Gurculioides 

 Buckland are Carboni- 

 ferous examples. 

 The order Pseudoscorpionida also known as Chernefidea or Chelonetni (False 

 Scorpions), is chiefly Recent, with no fossil representatives older than the Tertiary. 

 In this group the head is fused with the thorax, the abdomen is segmented and 

 broadly joined to the cephalothorax. Chelicerae chelate, with openings on the 

 movable finger for the ducts of the spinning glands ; pedipalpi chelate. The Recent 

 genus Chelifer Geotfr. (Fig. 1519) occurs also fossil in Baltic amber. 



The order Araneida or Araneae (Spiders) has numerous fossil representatives, 

 the earliest of which appear in the Carboniferous. Head and thorax fused ; 

 chelicerae two-jointed, retrovert ; pedipalpi pediform, their terminal joint in the 

 male modified as a copulatory organ ; abdomen segmented only in the most primitive 

 suborder, anteriorly constricted and movably united with the cephalothorax ; usually 

 six spinnerets present on the abdomen, but their number may vary between two 



Fio. 151S. 



I'lilyoi'hera iwui alata Scud. Coal Measures ; 

 Mazon Creek, Illinois. <*/2 (after Petrunke- 

 viteli). 



Fig. 1519. 



Chelifer hemprichi Menge. 

 Oligoceiie; Baltic amber, y/i. 



