26 AFRICAN FRESH-WATER CRABS— M. J. RATHBUN. vol. xvii. 



spines on the inner margin. Hand slightly inflated- npper margin 

 straight, lower slightly convex. Fingers irregularly toothed and 

 almost touching. Ambulatory legs rather slender, flattened; propodal 

 joints indistinctly spinulous on the margins. 



Measurements. — (No. 18005, two females). Length of larger speci- 

 men, 21.5 mm. ; width, 29.5. Length of smaller specimen, 19; width, 27. 



This species, in its three lateral teeth, resembles P. jywcilei, A. 

 Milne-Edwards, but differs from that species in its narrower and more 

 quadrate carapace and interrupted postfrontal crest. 



ERIMETOPUS, new geuus. 



Carapace arcuate anteriorly, quadrate posteriorly, moderately con- 

 vex. Front advanced beyond the antennular cavities, composed of 

 two distinct rounded lobes. Orbits narrow; eye stalks tapering to the 

 extremity. Postfrontal crest short and inconspicuous, or wanting. 

 Lateral margins spinous. The merus of the maxillipeds is transverse, 

 the anteroexternal angJe rounded, the palpus articulating at the inter- 

 nal angle, which is very slightly notched. Chelipeds with a row of 

 spines on the anterior margin of the carpus. Ambulatory legs with 

 margins spinous. 



ERIMETOPUS SPINOSUS, new species. 



Carapace about four-fifths as long as broad, convex longitudinally, 

 posterolateral margins long, sloping slightly inward and backward, 

 antero-lateral margins arcuate. The cardiac region and the posterior 

 portion of the gastric region are outlined by shallow depressions. 

 Front about one-third the width of the carapace,, advanced, two-lobed, 

 lobes separated by a broad V-shapecl .siniLts. ^]>Iargin of front and orbi ts 

 granulous. Orbits well-defined, the outer angle a sharp incurved 

 spine. There are two protogastric lobes, little elevated and often not 

 discernible, except by two transverse lines of a lighter color. A very 

 shallow median groove extends backward from the frontal margin and 

 forks directly behind the protogastric lobes. The postfrontal crest, 

 when present, is short, arcuate, tuberculous, and indistinct. It begins 

 back of the cornea and for a short distance is nearly straight, directed 

 outward and slightly forward, then curves almost jiarallel to the antero- 

 lateral margin. In most specimens, however, the crest is obsolete, 

 indicated only by the smoothly-rounded elevation behind the orbit, 

 Antero-lateral margin with a row of from 5 to S spines next the orbit, 

 of which the orbital spine is the largest. The spines are irregular in 

 size and position. On the anterior branchial region are 5 or more mar- 

 ginal spines separated by a space from the hepatic spines: the antericir 

 is by far the larger, and is sometimes bifid. The others decrease in 

 length posteriorly. The suborbital margin is granulous except at the 

 notch beneath the postorbital spine. The abdomen of the female 

 covers the sternum. 



