300 Records of the Indian Museum. [Voi.. VIII, 



Dec. 31st, 191 1. One male from Upper Rotung, collected by 

 Capt. de Courcy (Regd. no. ^). 



Jan. 9th, 1912. Three specimens, one & and two 9 , from the 

 Egar stream between Renging and Rotung (^--). 



Jan. loth, 1912. Three specimens, one & and two 9 , from 

 the Lalek stream near Renging (^^). 



Feb. 6th-i2th, 19 12. Two males from the neighbourhood of 

 Rotung, collected by Capt. de Courcy (^). 



Feb. nth, 1912. Sixteen specimens, nine & and seven 9 , 

 some with symbiotic Temnocephalidae, in small streams between 

 two and three miles S. of Yembung (^-^, types). 



March 21st, 1912. Six specimens, five & and one 9 , in the 

 Sirpo valley between Janakmukh and Renging (^)- 



March 26th, 1912. Two males in a stream near Balek (^^). 



Potamon (Geotelphusa) superciliosum, sp. nov. 



(Plate xviii, figs. 15-18.) 



This species is allied to P. adiatretum but differs in the follow- 

 ing particulars : — 



1. The carapace has much the same proportions but the front is 



less deflexed and posteriorly the surface is slightly flatter, 

 with the divergent branches of the cervical groove on 

 either side of the mesogastric area more conspicuous. 



2. The epigastric and post-orbital crests are well defined and 



separated in most cases by a rather definite groove. The 

 post-orbital crests arc specially prominent and exist as a 

 thin but salient ridge which disappears before reaching the 

 lateral margin (fig. 15). 



3. In young specimens the epigastric and post-orbital crests and 



the surface in the vicinity of the antero-lateral margin are 

 finely rugose, and the oblique wrinkles on the side walls of 

 the carapace are much more conspicuous. In very large 

 examples the rugosity of the crests is diminished though 

 traces of it are always found near the antero-lateral 

 margin. 



4. The epibranchial tooth, wholly absent in P. adiatretum, is 



represented by a small and inconspicuous nick in the finely 

 crenulate antero-lateral ridge, the latter being sharper and 

 better defined even than in the Abor specimens of the 

 preceding species (fig. 16). 



5. There is, as in P. adiairctuui, no trace of an external orbital 



tooth, but the lower border of the orbit does not run quite 

 flush into the upper border, the two margins joining at 

 slightly dift'erent levels. 



In young specimens the outer surfaces of the carpus and chela 

 are strongly pitted, but statcely any trace of this remains in adult 



