DUTCH BORNEO-EXPEDITION. 159 



As has beeu indicated in my paper quoted above, this 

 species , that hitherto was only known to inhabit the lakes 

 and rivers of Sumatra and Western Java, exhibits consi- 

 derable variation in the characters of the rostrum and of the 

 second pair of legs. The measurements given below prove that 

 also the form of the ambulatory legs is varia- 

 ble, that their joints appear rather robust in some indi- 

 viduals , as e. g. in the adult male from the Upper-Sibau , 

 in others tolerably slender, as in the adult female from 

 Sintang. The same variation is exhibited by specimens 

 from Sumatra, which are before me, as may be seen by 

 comparing the specimens from the lake of Singkarah with 

 those of the lake of Manindjau. 



Palaemon pilimanus belongs to those species the ferti- 

 lized eggs of which are large. The eggs of the two fe- 

 males from Sintang , one of which is adult , the other of 

 middle size, are equally large, viz. 1,8 mm. long and 1,1 

 — 1,2 mm. broad; those carried by the small female from 

 the Ketoengau river that is only 30 mm. long, have 

 the same size. The eggs of Sumatra-specimens are also 

 2 mm. long (de Man, 1. c. p. 472). 



The largest specimen , the male collected in the Upper- 

 Sibau river, is 60 mm. long from the tip of the rostrum 

 to the end of the telson. The formula of the rostrum , that 

 reaches to the end of the antennular peduncle, is A, the 

 fifth tooth is placed above the orbital margin and the 

 rostrum is directed slightly downwards. The rostrum of 

 the adult female from Sintang extends straightly forwards , 

 as far as in the preceding specimen , and its formula is 

 1 3 ; the teeth above the eyes stand closer together than 

 the proximal and distal ones. For the other female the 

 formula is i_3 and for the three males 9 , u and u ; for 



2 2 2 1 



the male from Nanga Raoen it is i '. and for the female 

 ij. Like the specimens from the Ketoengau river, those 

 that were collected at Sanggau are all young, of small size 

 and 25 — 30 mm. long, though some already carry eggs. 



Notes from th.e Leyden IMuLsevina, Vol. XX. 



