ANTHRACOMARTUS. 63 



Generic Characters. — Carapace high ; the median portion of its upper surface 

 nearly flat or slightly excavated ; the lateral and anterior portion sloped nearly 

 vertically downwards to the lateral and anterior border ; the posterior portion 

 much more gradually sloped backwards to the groove which defines the posterior 

 border ; this border straight or slightly emarginate ; the posterolateral angles 

 rectangular ; the lateral borders subparallel for more than half their length, but 

 converging anteriorly from a point approximately on a level with the articulation 

 of the legs of the second pair, to form an angular prominence over the mandibles ; 

 the edges of the flattened dorsal area defined by a marked ridge which exhibits 

 anteriorly a low and short crest or thickening, perhaps marking the position of the 

 lateral eyes ; the descending portion in the middle line in front compressed or 

 defined by a pair of grooves which pass downwards to the marginal angle above 

 the mandibles. 



Opisthosoma and limbs constructed as described under the diagnosis of the 

 family. 



Type Species. — Anthracomartus voelkelianus, Karsch, from the Coal Measures of 

 Silesia. 



Generic value has been assigned to the characters presented by the carapace, 

 because it appears to me probable that A. palatinus, Amnion, if the figure is to be 

 trusted, will have to be separated from Anthracomartus on account of the difference 

 in the shape of the carapace, which is much wider than long, somewhat constricted 

 posteriorly, and has the antero-lateral angles widely rounded. Moreover, the 

 antero-lateral angles of the opisthosoma project prominently beyond the postero- 

 lateral angles of the carapace. Amnion detected a pair of median eyes near the 

 front of the upper surface of the carapace in his species. No such eyes were 

 seen in any of my specimens. 



It is needless to repeat here the reasons I have already published for regarding 

 Promygale as a synonym of Anthracomartus (see Geol. Mag. [5], vol. vii, pp. 505 — 

 508, 1910). 



The chief distinctive features of the two species of this genus described below 

 may be briefly epitomised as follows : 



a. Total length of adult from about 21 to 25 mm. ; seventh tergal plate of opisthosoma 

 larger, the length of its median area approximately equal to its anterior width ; the 

 triangular lateral pleural plate correspondingly long . . . hindi. 



a. Total length of adult from about 10 to 12 mm. ; seventh tergal plate of opisthosoma 

 smaller, the length of its median area much less than its anterior width; the 

 triangular lateral pleural plate correspondingly short . . . jpriesti. 



Neither of these can be identified, at present, with any described form. 



