DESCRIPTIONS OF A NEW GENUS AND TWO NEW SPECIES 

 OF AFRICAN FRESH- WATER CRABS. 



By Mary J. Rathbi n. 



Aid, Department of Marine Inrertehrates. 



The crabs described below were found in imid under boards and 

 timbers by Mr. ,1. II. Canij) at Stanley Pool, Congo, West Central 

 Africa. 



Family Thelphusid^. 



PARATHELPHUSA CAMPI, uew species. 



Carapace subquadrilateral, conspicuously punctate. Depression 

 between the gastric and cardiac regions deep. Protogastric lobes prom- 

 inent, separated by a median groove whicli extends backward from the 

 frontal margin. The ])ostfrontal crest begins behind the base of the 

 eyestalk and is continued to the lateral margin ; it is finely denticulate 

 and is almost straight, sloping backward and outward. Front a little 

 more than one-third the width of the carapace, deflexed, divided by a 

 very shaUow sinus into two lobes, with a raised margin, which is con- 

 tinued to the postfrontal crest. Superior orbital margin sinuous, 

 advanced in its middle portion. Postorbital tooth acute, prominent. 

 Lateral branchial spines three. In one of the two specimens there is a 

 spinule between the first and second spines, and a short fourth spine on 

 the left side. Between the first spine and the postfrontal crest there 

 are two or three spinules forming a short ridge in the same line with 

 the postfrontal crest. From the last spine a raised line extends back- 

 ward upon the carapace, and is followed by several broken parallel lines. 

 The inferior margin of the orbit is rather deei)ly rounded below the outer 

 angle; from that point the margiu is directed inward and forward; the 

 inner angle is obtuse; the margiu is set with a row of bead-like gran- 

 ules. The terminal segment of the abdomen of the female is subtri- 

 angnlar, and the length is nearly half the width. The merits of the 

 niaxillipeds is very transverse, the antero-external angle r<mnded, the 

 antero-internal angle not deeply cut. 



Chelipeds of female unecjual; merus rugose above, inner margin 

 tuberculous, with a sharp spine just below the margin ; carpus with two 



Proceedinss National Museum, Vol. XVll — No. 980. 



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