R. I. Pocock — A Neiv Carboniferous Arachnid. 251 



cast that I see no escape from the conclusion that it represents the 

 anal orifice. Hence the anal somite is complete with respect to its 

 tergal and sternal elements. In Eophrynus, therefore, eleven terga 

 and ten sterna can be made out in the opisthosoma. The first tergal 

 plate, which has no sternal representative, I homologised with the 

 tergum of the pregenital somite, and the second, with the corresponding 

 first sternal plate, with the tergum and sternum of the genital somite 

 in Phrymis or the Pseudoscorpiones. A subsequent study of the 

 Opiliones, however, has suggested an alternative interpretation of 

 these plates which divorces JEopTirynus from the Pedipalpi and brings 

 it more into touch with the members of the former order, \yith which 

 the structure of the appendages of the prosoma and of the segments 

 of the opisthosoma forcibly suggests the Anthracomarti to be nearly- 

 related. In Kreischeria, Brachypyge, and AntJiracomartus, for instances- 

 only ten terga ancl^ nine sterna seem to be distinguishable in the 

 opisthosoma, the difference in the number of segments in this region 

 between these genera and JEophrynus being attributable to the dis- 

 appearance, either by fusion or excalation, of the first tergal and the 

 last sternal plates that are traceable in the latter genus. And when 

 it is remembered that ten terga and nine sterna are also found in the 

 opisthosoma in the Cyphophthalmous Opiliones, that the tergum of 

 the eighth forms the posterior extremity of the dorsal surface, and 

 overlaps that of the ninth, which, with its corresponding sternum, is 

 reduced to an annuliform preanal sclerite, and that the tenth or last 

 tergal plate has no sternal equivalent, but closes like a valve over the 

 anus and is encircled in the way just described, exactly as occurs 

 apparently in Anthracomartus and Brachypyge, it is difficult to doubt 

 that the segments of the opisthosoma correspond each to each in 

 the Cyphophthalmi and the genera of Anthracomarti just mentioned. 

 If this be so, the first tergum and the first sternum in Anthraco- 

 martus, Kreischeria, and Brachypyge will correspond to the tergum 

 and sternum of the first post-genital somite in Phrynus. In that case 

 the genital aperture in the Anthracomarti must have opened in front 

 of the first sternum, as it does in the Opiliones, and not behind it as 

 I assumed in my former paper. JEophrynus is peculiarly interesting 

 in this connection because it appears to be the only known genus of 

 Anthracomarti that has retained an unmistaheable trace of the genital 

 somite, unless the suggestion that I made with regard to the first 

 tergal plate in Anthracomartus volJcelianiis and Kreischeria wiedei be 

 correct. 



In view of this new reading of the facts, the explanation of Fig. 1, A, 

 p. 490, of my previous paper may be emended as follows : — The plate 

 marked pregen. tg. will be the tergum of the genital somite, and the 

 plate marked 1 tg. (gen.) that of the first post-genital somite. 



This view of the matter was briefly alluded to in my paper upon 

 the classification of the Opiliones,^ and coincides with the explanation 

 of the morphology oi Leptopsalis, one of the genera of Cyphophthalmi, 

 put forward by Borner six months earlier.* 



1 Ann. Mag. Nat. Hist. (7), x, pp. 504-515, December, 1902. 



2 Zool. Anz., June, 1902. 



