B. I. PococTi — The Carboniferous Arachnid Anthracosiro. 407 



of these plates is elevated in tte form of a triangular crest; that 

 of the eighth is tubercular ; and since the impression exhibits 

 a multitude of close-set punctures upon the terga, it may be inferred 

 that these plates were finely granular. This granulation is not 

 apparent in A. woodioardi ; but, as in that species, there is a row 

 of coarser granules along the posterior border of the terga"and of 

 their laminee, at least in the hinder half of the body. There is also 

 a very distinct joint between the lateral laminae of the eighth tergal 

 plate and the area from which they arise. These joints are not 

 visible in A. ivoodwardi. Towards the lateral border of the laminge 

 of the fifth, sixth, seventh, and eighth terga thei'e is a distinct 

 longitudinal groove ; the area lying externally to this is bent 

 upwards so that the dorsal surface of the opisthosoma is posteriorly 

 scoop-shaped. The sculpturing of this area of the laminge is more 

 coarsely tubercular than the rest of the terga. 



Total length 6*5 mm. ; width of opisthosoma about 3 mm., length 

 of prosoma 2 mm. 



Since there is no reason to suppose that the differences between 

 this specimen and the type of A. ivoodwardi, apart from the great 

 discrepancy in size, can he attributed to age, there is no choice but 

 to regard the two as representatives of distinct species. I propose 

 to name this new form Anthracosiro fritschii, after Dr. A. Fric of 

 Prague. 



The characters of the two may be tabulated as follows : — 

 a. Terga of opisthosoma not granular throughout ; the first large, 

 more than half the length of the second, which has its 

 anterior border mesially emarginate ; joints between the 

 proximal extremity of the lateral laminse and the median 

 area of the eighth tergal plate not apparent. Length from 

 17 to 21 mm. ... ... ... ... woodwardi, Voc. 



h. Terga of opisthosoma finely and closely granular; the first 

 very short, much less than half the length of the second, 

 of which the anterior border is straight from side to side ; 

 joints between the laminge and the median area of the terga 

 of the eighth segment present. Length about Q-B mm. 



fritschii, sp.n. 

 The two additional specimens of Anthracosiro, especially the one 

 last described, make it possible to give a far completer diagnosis 

 of the genus than could be based upon the single example of 

 A. woodwardi. Pending the discovery of specimens showing fully 

 the structure of the appendages and the ventral surface of the body, 

 the diagnosis may run as follows : — Carapace vaulted, with a wide 

 depression in the middle of its dorsal surface and a very short 

 posterior transverse area. A pair of widely separated ocular 

 tubercles in its anterior half. Upper side of opisthosoma presenting 

 eight tergal plates, which are without tubercles, but are marked 

 with a pair of muscular impressions ; the first much shorter than the 

 second ; their anterior and posterior borders transverse, subparallel, 

 scarcely or only slightly recurved at the posterior end of the body ; 

 lamina rhomboidal, small at the anterior end of the body, 



