48 TERRESTRIAL (CARBONIFEROUS ARACHNIDA. 



the tergnm of tlie teiitli seo^uieut. Ventral surface of opistliosonia typically ^vitll 

 seven sternal plates; the last three large and corresponding to the last three terga; 

 the anterior fonr corresponding to the anterior six terga. The first and second 

 sterna small and visible in the intercoxal space of the legs of the last pair, the first 

 being triangnlar. Apparently a small orifice, the genital orifice, situated at the 

 anterior extremity of the first and behind the sternal area of the prosoma. 



Sternal area of prosoma narroAV, much longer than wide, and consisting of 

 five small plates, one pair between the coxfe of tlie legs of the third and fourth 

 pairs, a second pair between those of the second legs and a small unpaired plate 

 just behind the contiguous coxfie of the legs of the first pair. 



Coxce of the four pairs of legs large, triangular, and wedge-shaped, occupying 

 the whole ventral area of the prosoma, with the exception of the narrow sternal 

 region; each leg consisting of seven segments, including the coxa; the second 



Fig. 18. — Geraphrynns carhonarius, Seudder ; diagraniniatic restoration of the dorsal surface of the type 

 specimen, adapted from Sciidder's figure (Proc. Boston Soo. Nat. Hist., vol. iv, pi. x.fig. 10), the dotted 

 lines representing tlie coxal and sternal sclerites underlying the carapace, nearly three times nat. size. 

 — Coal Measures; Mazon Creek, Illinois, U.S.A. 



segment (trochanter) stout ])ut short; the remaining segments thinner and longer, 

 and not very unequal in length, with the exception of the seventh or tarsus, which 

 is rpiite short, the fourth segment or patella being long, and not short as in the 

 Opiliones. Palpi very short, probably six-jointed, their basal segments concealed 

 from below by the united coxse of the legs of the first pair. 



Ti/j^e Species. — Geraphrnmis cdrhonarius, Seudder. 



This generic diagnosis is based for the most part upon the British material of 

 this genus that I have seen, checked by comparison with Scndder's figure of the 

 type specimen of the typical species of the genus, (A carhonarius. Judging from 

 this figure, G. carhonarius differs from all those described in this paper in the largo 

 size of the carapace as compared with the opisthosoma, the median length of the 

 former exceedino- the median leng^th of the latter. 



It is impossible to say with certainty how many species are represented l)y the 



