98 CRUSTACEANS 01' THE 



distal end, those of the last pair are a little punctate, 

 smooth. The two following joints are also rugose exter- 

 nally ; the crest on the outer surface of the earpopodites 

 is well-marked except on the legs of the last pair and the 

 propodites present a longitudinal groove in the middle] of 

 their outer surface. The last joints are stout, elongate, a 

 little longer than the propodites, well armed with 

 small spines and slightly arcuate towards their extremities. 



The cephalothorax has a light violet colour, the legs 

 are yellowish red. 



Amongst the type-specimens that I received from the 

 Zoological Museum of Göttingen is also a female, without 

 eggs, of that species that was referred by Burger (in : Zoolog. 

 Jahrbücher, herausgegeben von J. Spengel, Abth. f. System. 

 V. 8, 1894, p. 2) to Potamon sinuatifrons. It belongs 

 certainly to this species for there are no other differences 

 from the type-specimens from the Paris Natural History 

 Museum than with regard to the dactylopodites of the 

 ambulatory legs. According to the measurements these 

 joints indeed appear comparatively a little longer and so- 

 mewhat narrower than in the Paris types. Burger referred 

 his specimens with some doubt to Pot. sinuatifrons^ for 

 he was misled by the figure of this species in the »Nou- 

 velles Archives du Muséum", that is inexact as shows at 

 first sight a comparison with my figures (Plates 8 and 9, 

 Fig. 9). Potamon sinuatifrons proves consequently to in- 

 habit the Philippine Islands (Zamboanga and Rio 

 Jibon): the habitat was hitherto remained unknown. It is 

 represented in Central Borneo by Pot. maliakkamense and 

 Pot. consohrinum. 



Measurements in mm. : 12 3 4 



Q ^ c^ ^ 



Breadth of the cephalothorax 61 53 36 41 



Length „ - 45 39 26'- 30^ 



Distance between the ext. orbital angles .... 33i 314- 22^- 26^ 



Breadth of the frontal margin 14 12^ 8^ 10 



Distance between the epibranchial teeth .... 44 37| 27j^ 31^ 

 Distance between the external orbital angle and 



the epibranchial tooth ó^ 3J- 2^ 3 



I^otes from the Leyden Museum, Vol. XXI. 



