DUTCH BORNEO-EXPEDITION. 131 



smaller. The other chela is smaller, but for the rest agrees 

 with the right. 



The ambulatory legs are sleuder and moderately long, 

 so are e. g. those of the penultimate pair a little more 

 than twice as long as the cephalothorax. The meropodites 

 of the penultimate pair are 4-times as long as broad, their 

 upper margin is slightly rugose, but devoid of a tooth at 

 the distal end and their outer surface is nearly smooth. 

 The propodites of this pair are about 3-times as long as 

 broad, they show a few small spines along their posterior 

 margin, but they are also smooth. The terminal joints 

 of the penultimate legs are 6-times as long as broad at the 

 base, slightly longer than the propodites and taper rather 

 regularly towards the slightly arcuate tips; some small 

 spinules are observed along their margins. The three ter- 

 minal joints of the ambulatory legs are also smooth and 

 glabrous. 



The cephalothorax is lead-coloured, the legs are lighter 

 and yellowish marmorate. 



Fotamon Dehaani may at first sight be distinguished 

 by its less enlarged cephalothorax, that is considerably 

 longer in proportion to its breadth. The antero-lateral 

 margin is more coarsely granulate and one of these gra- 

 nules is sometimes more prominent than the others and 

 then appears as a rudimentary epibranchial tooth, but in 

 other specimens there is no trace of such a granule. The 

 lateral ridges, traces of the postfrontal crest, that are 

 observed in Pot. hicristatum, are quite absent in the 

 Japanese species. The oblique rugosities on the postero- 

 lateral margins are indistinct or quite wanting in Pot. 

 Dehaani. The posterior margin of the cephalothorax is 

 much broader in the Borneo-species than in the other 

 and so still other differences might be enumerated. 



Potamon ohtusipes Stiraps. from the Japanese island of 

 Ousima is also different, I think. According to measure- 

 ments of this species published some time ago (de Man, 

 in: Max Weber, Zool. Ergebnisse einer Reise uach Nieder- 



Notes froiTi the Leyden ÜMuseum, "Vol. XXI. 



