576 



ARTHROPODA. 



separated from one another, and the former is usually composed of 

 more or fewer wedge-shaped, foot-bearing segments. The abdomen 

 consists of from four to nine somites, and the " palpi " are not 

 much longer than the legs, and are not terminated by pincers or 

 claws (Scudder). Of the genera included in this extinct group, all 

 of which are confined to the Carboniferous period, Architarbus 

 (fig. 432, b) is found in the Coal-measures of both Europe and 

 North America. In A. subovalis the cephalothorax is shorter than 

 the abdomen and carries four pairs of legs and a pair of palpi, the 

 form of which is unknown. The abdomen consists of nine seg- 



Fig. 432. — a, Eophrynus Prestvicii, viewed ventrally, and somewhat enlarged— Carboniferous; 

 B, Architarbus subovalis, enlarged four times, and viewed from below — Carboniferous (after H. 

 Woodward). 



merits, of which the anterior ones are much narrower than the 

 hinder ones. In Anthracomartus, also distributed in the Coal- 

 measures of Europe and North America, the cephalothorax is quad- 

 rangular, and is only about half as wide as the abdomen, the latter 

 region consisting of seven segments. In Arthrolycosa, from the 

 Coal-measures of Illinois, the cephalothorax, on the other hand, is 

 round, and is much larger than the abdomen, the latter region con- 

 sisting of seven distinct segments and being comparatively narrow. 

 Lastly, in the singular genus Eophrynus (fig. 432, a), the cephalo- 

 thorax is triangular and extended in front, and carries the four pairs 

 of legs and a pair of slender palpi. The abdomen is twice as large 



