VOL. XII, PP. 27-30 JANUARY 27, 1898 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



DESCRIPTIONS OF THREE NEW SPECIES OF FRESH 

 WATER CRABS OF THE GENUS POTAMON* 



BY MARY J. RATHBUN, 



Of the three species here described, one is a typical Potamon, 

 in which the postfrontal crest is. developed but interrupted ; the 

 other two belong to the subgenus Geothelphusa^ without a post- 

 frontal crest. The first, P. abbotti^ is from the Malayan Peninsula, 

 and is related to a group of Indian species described by Wood- 

 Mason. The second, P. (Geothelphusci) levicervix, was taken at 

 the Loo Choo Islands with P. (.) dehaanii (White) and P. ((7.) 

 oblusipes (Stimpson), by a Japanese collector, Mr. F. Sakamoto, 

 and forwarded to the U. S. National Museum by Mr. Garrett 

 Droppers. The third species, P. (6r.) macropus, is notable as 

 being the first member of the subgenus taken on the west coast 

 of Africa. The other African species of Geothelphusa are Potamon 

 (Geothelphusa) berardi (Savigny) from Egypt, P. (6r.) socotrensis 

 (Hilgendorf) from Socotra, and P. ((7.) emini (Hilgendorf) from 

 Victoria Nyanza. This last has faint indications of a crest, but 

 so also has P. dehaanii (White), which is one of the two original 

 species of Geothelphusa. On account of the presence of this 

 feeble crest in P. dehaanii, it were better to consider P. obtusipes 

 (Stimpson) as the type of the subgenus Geothelphusa. 



Potamon abbotti sp. nov. 



PI. I. 



Cervical suture obsolete ; sabbranchial regions distended Laterally ; merus oj 

 maxillipeds as long as wide. 



* Published by permission of the Secretary of the Smithsonian Insti 

 tution. 



6 BIOL. Soc. WASH., VOL. XII, 1898 (27) 



