APHANTOMARTUS. 79 



inner portion of the median of the three laminas is apparently smooth; all the 

 tubercles irregular in size and more or less anastomosing; the central groove 

 smooth. The entire dorsal surface of the opisthosoma covered with tubercles of 

 varying size, which on the obverse show up as a number of pits separated by a 

 network of ridges. Each of the posterior seven tergal plates, with exception of 

 the seventh, divided more or less distinctly into five areas, a median elevated area, 

 the pleural lamina on each side, and an intermediate area separated apparently by 

 a joint from the pleural lamina, but only by a groove from the median more 

 elevated area; the latter with two large tubercles, one on each side of the middle 

 line, in addition to the smaller tubercles ; the intermediate areas and the pleural 

 laminas each with one large tubercle, so that in all there are six rows of large 

 tubercles on the dorsal surface. The structure of the seventh tergal plate is 

 obscure; there are possibly two large tubercles on its median area, but there 

 appear to be none on its pleural and median laminae. The opisthosoma is evenly 

 ovate in outline, being widely rounded in front, with its posterior extremity 

 narrower and more truncated, and armed apparently as in Eophrijnus with two pairs 

 of short spiniform processes. The seventh tergal plate from the end, i. e. the 

 first of the terga invariably shown in the Anthracomarti, is considerably longer 

 than those that succeed it, but is otherwise similar to them, except that its 

 intermediate area is marked in front with a groove defining a small lanceolate 

 area. In front of this tergal plate there is a large plate with convex anterior 

 border and marked with a transverse sinuous groove dividing it into an anterior 

 shorter and a posterior longer portion, each of which may perhaps represent a 

 tergal element ; the posterior longer area has a distinct but small and triangular 

 pleural lamina. 



Measurements in mm. — Total length probably about 26; width of carapace 

 about 10; length of opisthosoma 18, width 14 - 5. 



Coal Measures of South Wales; Craigola Vein about 200 yards S.W. of 

 Glyn-coch Farm. 



Type and only known specimen (Nos. 25,020, 25,021) in the Museum of the 

 Geological Survey, Jermyn Street. 



Genus APHANTOMARTUS, nov. 



Generic Characters. — Carapace with its median area longitudinally oblong and 

 elevated; the elevated area divided with a transverse groove into two subequal 

 portions, and marked with a deep median groove which passes forwards from the 

 posterior border of the posterior portion on to the anterior portion, where it 

 bifurcates on each side of the median ocular tubercle, which is situated 

 near the anterior border of the anterior area. This tubercle bears a pair of eyes. 



