80 



CRUSTACEANS OF THE 



Distance between the anterior frontal margin and 

 the tip of the median tooth of the epistome. 



Length of the terminal segment of the male abdomen 



Length of the penultimate segment 



Breadth of the anterior margin of this segment. 

 » // n posterior ,/ „ „ ,, 



Horizontal length of the larger chela .... 

 II 1 ,1 „ fingers 



Height of the hand at the articulation of the fingers 



Length of the meropodites -^ 



Breadth „ „ „ § '3 o. 



Length of the propodites in the middle . i=- ^^ 



Breadth » » » ,, „ ,, 



Length of the dactylopodites '^ 



a 



Potamon (Perithelphusa) silvicola, n. sp. 

 (Plate 7, Fig. 6). 



Four males about of the same size aud two youoger females 

 without eggs, were collected in March and May 1894 in 

 a forest near Nanga Raoen and in the following month 

 one quite young male was captured at Poetoes Sibau. 



This species is closely allied to Pot. borneense v. Mart, 

 and its variety hilaris, and bears a great resemblance to 

 them, but it differs more from Pot. Bilttikoferi, at first 

 sight by the different general outer appearance. It may 

 be distinguished from the first named species and its va- 

 riety especially 1° by the cephalothorax being a 

 little longer in proportion to its greatest 

 width, 2° by the different shape and length of the 

 extraorbital teeth. 



The third specimen, the carapace of which is 32 '/2 mm. 

 broad, was sent to Prof. Hilgendorf at Berlin, who com- 

 pared it with the type of Pot. borneense v. Mart, and then 

 wrote me the differences. 



The carapace is little enlarged, being little longer than 

 three fourth the greatest width and it is constantly so- 



Notes from the Leyden IMuseuiu, Vol. XXI. 



