14 



TERRESTRIAL CARBONIFEROUS ARACHN1DA. 



Eobuthus holti, sp. nov. Plate II, fig. 2; Text-figure 1. 



The sternum of the prosoma is semi-elliptical, convex, rounded in front and 

 truncated behind. Abutting against it on each side there is a large coxal segment 

 belonging to the legs of the third or fourth pairs. Following the sternum there is 

 a conspicuous bivalved genital operculum resembling in a general way that of 

 recent Scorpions ; and on each side of this there appears to be a segment (or 

 segments) of a limb, which does not, however, resemble the coxa of the fourth leg 

 in recent Scorpions, which always abuts against the sternum of the prosoma. If 

 it does not belong to the fourth leg, I can only suggest that it represents the 

 external ramus of a pair of appendages belonging to the genital segment, the 



St. 



Fio. 1. — Eobuthus holti, sp. n. ; partially restored and slightly magnified from the type specimen. — Coal 

 Measures ; Sparth, near Kochdale. F. Holt Collection, ex., coxa of 3rd leg, possibly fused coxoe of 

 3rd and 4th legs ; g., genital operculum ; pect., one of the pectines, its exact structure being 

 doubtful ; scl., sclerites abutting against genital operculum and probably representing either the basal 

 segments of a leg of the 4th pair or the lateral ramus of the appendage of the 1st somite of the 

 opisthosonia ; st., sternum of prosoma; st. pect., sternum of pectinal somite; st. 3 to si. 7, st rna 

 of the 3rd to the 7th somites of the opisthosonia, the exact shape of the 3rd being doubtful. 



two halves of the genital operculum being the internal rami. In this connection 

 it must be remembered that the genital operculum of Limulus polyphemiis consists 

 of a pair of inner and a pair of outer branches or rami. Behind the genital 

 operculum follows a moderately large plate, nmcliAvider behind than in front. This 

 is the sternum to which the pectines are attached. One of the latter attached to its 

 posterior border is traceable, but the details of its structure, apart from its shape 

 and the presence of numerous small teeth, are too faint to figure or describe Avith 

 assurance. 



Of the five posterior sterna of the abdominal portion of the opisthosonia, the 

 first appears to be rather small and to be overlapped by the sternum and pectines 

 of the segment in front of it. I cannot find evidence that its posterior border is 

 bilobed ; but the posterior borders of the three succeeding sterna are markedly 



