DUTCH BORNEO-EXPEDITION. 119 



The specimen from Mount Kenepai, that I described 

 above as a new species, Potamon kenepai^ is closely allied, 

 but seems to belong to a different species. The cephalo- 

 thorax, indeed, is slightly longer in proportion to its breadth, 

 less expanded laterally at the level of the anterior branchial 

 region and less narrowed posteriorly. There exists a rudi- 

 mentary epibranchial tooth. The epigastric lobes are more 

 prominent and the front is a little less broad. The median 

 lobe of the posterior margin of the epistorae is less pro- 

 minent, broadly rounded. The distance, finally, between the 

 anterior extremity of the abdominal cavity of the male 

 and the posterior margin of the buccal frame is distinctly 

 shorter than the distance between the anterior extremity 

 of the ischial line on the outer foot-jaws and the external 

 margin of the ischium. The fingers of the larger chela 

 appear very finely granular under a lens, in Pot. hender- 

 sonianum, however, this minute granulation is scarcely 

 perceptible. 



Potamon {Geothelphusa) montanum Burger, from the island 

 of Luzon, a male type-specimen from the Göttingen Mu- 

 seum is lying before me, is a different species. The cepha- 

 lothorax is not enlarged posteriorly, so that the postero- 

 lateral margins are not concave , as is the case in the 

 Borneo-species. The oblique wrinkles on the lateral mar- 

 gins are shorter, less distinct and the oblique, lateral por- 

 tions of the cervical groove are almost completely wanting. 



The extra-orbital angle is less prominent. The free- border 

 of the front has a different shape and the posterior margin 

 of the epistome is much deeper notched on each side of 

 the median process. The orbits are higher in proportion 

 to their breadth , and have a different form ; the male 

 abdomen has also another form, sternum and abdomen are 

 much more coarsely punctate. The ambulatory legs finally 

 are more slender than those of Pot. hendersonianum. 



Burger is quite wrong when he describes the cephalo- 

 thorax as being not punctate: the punctulations, on the 

 contrary, are quite distinct. 



Notes from tlie Leytlen Museum , Vol. XXI. 



