82 TERR1^]STRIAL CARBONIFEROUS ARACHNIDA. 



in the Museum of the Geological Survey, Avhich I regard as the posterior portion 

 of the ventral surface of the opisthosoma of the same species. It is somewhat 

 strongly convex from side to side, and like the ventral surface of EopJm/iiiis 

 prestvicii appears to be smooth, except for a few small symmetrically-arranged 

 tubercles. The posterior portion of the fossil, however, is marked with a network 

 of ridges, which I interpret as the pattern of the dorsal surface shown by the 

 crashing of the sterna on the terga. The anal operculum is subterminal. In 

 front of it there are seven concentrically curved |)lates, with the concavity of their 

 posterior borders looking backwards ; the first and second of these are much 

 shorter than those that succeed them, the latter being subequal in length. The 

 second plate is as wide as the third ; the first, however, is much narroAver, and 

 tapers away to a point laterally. Total length and Avidth about 5 nun. 



A third specimen in the same collection (No. J. P. 402 — 403), also from the 

 Mynyddislwyn vein in the Lebanus Colliery, by the roadside, two-thirds of a mile 

 N. of Tredegar Junction, is represented by the posterior six segments of the 

 opisthosoma, shoAving the characteristic sculpturing clearly on some of the plates. 

 The total length and width are about 4*5 mm. 



The species described by Scudder as Anthracomarfii^ pitsfnlatits (Proc. Amer. 

 Acad. Arts Sci., a'oI. xx, p. 18, 1884; Mem. Bost. Soc. Nat. Hist., a^oI. iy, p. 452, 

 pi. xl, figs. 5 and 8, 1890) shoAVS many points of resemblance to this genus, and 

 possibly belongs to it. In any case it cannot be referred to Anfliraeoinavtus. This 

 specimen, from Mazon Creek, Illinois, appears to be either an impression of the 

 dorsal surface or the underside of the dorsal exoskeleton, the pattern being a 

 network of ridges circumscribing sunken polygonal " cells " or de})ressions. It 

 may be noted that the posterior borders of the pleural plates and of the terga are 

 in the same straight line, and that there is a long median grooA^e on the carapace 

 as in A[)]i(tiifnmarfiii^ areolafns. The pattern of the sculpturing, hoAVOA^er, is 

 different from that of the British species. 



Order OFILIONES or ANTHBACOMABTI {?). 



With considerable hesitation I refer to the Order Opiliones an Arachnid on a slal) 

 of shale from the Kiltoung Coal Seam, Ellismuir, sent to me by Mr. Robert Dunlop, 

 Avho discoA^ered it in 1888. It AA^as in Dr. Peach's hands for some time, but Avas 

 apparently never figured or descril)ed. The structural characters of the fossil are 

 not sufficiently well preserved to make their exact interpretation possible. Since 

 the surface is evidently closely granular I infer that the dorsal side is exposed, but 

 OAving to its being crushed, the outlines of the coxoj of at least the two posterior 

 |)airs of appendages are shown, and render obscure the form of the carapace in its 



