94 OX FRESHWATER CRl'STACEANS FJtOM NORTH BORNEO. [Feb. 0. 



Potamon (Paraihelphusd) eonvexa, de Man, Notes Levd. Mus. 

 xxi. p. 142 (1899). 



The single specimen seems, by the following characters, to belong 

 to this species : — 



i. There are two epibranchial teeth on each side, 

 ii. Tbere is a spine near the end of the merus in the wal king- 

 lets, 

 iii. The distance between the tip of the postorbital tooth and 

 that of the first epibranchial tooth does not exceed the 

 distance between the first and second epibranchial teeth. 

 iv. The outer edge of the first epibranchial tooth is strongly 



convex, 

 v. There are no spots on the carapace or limbs. 



The dactyles of the walking-legs are rather shorter and stouter 

 than is indicated in de Man's figure of the allied P. metadata. 

 The fingers of the chelae are dark in colour. P. convexa is already 

 recorded from Java, Timor, and New Guinea, and, doubtfully, from 

 Borneo 1 . P. maculata (de Man) 1879, is a closely allied form 

 from Sumatra. 



1 2 ; British North Borneo. 



'6. Potaho>* (Thelphusa) 2 consobrinum de Man. 



Potamon (Potanwn) consobrinum, de Man, Notes Level. Mus. xxi. 

 p. 99, pis. vi., ix., x. fig. 10 (1899). 



This species is already reported from Borneo (Mt. Damoes and 

 Upper Sibau Biver) by de Man. Ortmann (Zool. Jahrb. x. Syst. 

 p. 301) gives a list of allied forms and their distribution. 



2 <3 , 1 2 ; Kadamaian Eiver, Kim Balu, 2100 ft- et. 



4. Potamox (Geothelphusa) kada.maianum, n. sp. 



A single female specimen of a form allied to P. obtKsijh-s (Ntimps.) 

 1858, and P. dehaani (Gray) 1847, seems to deserve a name of its 

 own. Whether it were not better treated as a local race of one 

 of the above species, or all three as local forms of P. dehaani, is a 

 question to be settled when the subject of the interrelationship of 

 the various forms in the genus comes up for discussion. In the 

 meantime its distinctness seems quite as great as that of several 

 of the generally accepted species. It differs from P. obtugipes 

 in the greater slenderness of its legs, especially of the dactyles, 

 which are long and narrow and end in a sharp claw. The 

 branchial regions are tuberculate, and their hinder portions 

 rugose. The front is more finely tuberculate. The wrist and palm 

 are rugose-tuberculate. Behind each orbit is a shallow, triangular 

 depression of the carapace reaching backwards through rather le- s 

 than half the length of the cephalothorax, and separating the 

 branchial from the gastric region. 



1 Miers. Ann. Mag. Nat. Hist. (5) v. p. Mi Hi (1880). 



2 According to Ortmann (Zool. Jahrb. x. Svet. p. o(ld) Tkelphttsa is the 

 correct name for the subgenus in which this species should be placed. 



