48 TERRESTRIAL CARBONIFEROUS ARACHNIDA. 



the tergum of the tenth segment. Ventral surface of opisthosoma typically with 

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

 the anterior four 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 triangular. 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 narrow, much longer than wide, and consistino- of 

 five small plates, one pair between the coxa? of the 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 coxa? of the legs of the first pair. 



Coxa? 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 



Pig. 18. — Geraphrynus carlonarius, Scndder ; diagramiu.itic restoration of the dorsal surface of the type 

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

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

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



segment (trochanter) stout but short; the remaining segments thinner and 'longer, 

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

 is quite 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 coxa? of the legs of the first pair. 



Type Species. — Geraphrynus carbonarius, Scudder. 



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

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

 type specimen of the typical species of the genus, G. carbonarius. Judging from 

 this figure, G. carbonarius differs from all those described in this paper in the large 

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

 former exceeding the median length of the latter. 



It is impossible to say with certainty how many species are represented by the 



