2QA Records of the Indian Museum. [Vol. VIII, 



marked separation of the epigastric and post-orbital crests and 

 in the vestigial condition of the llagellum of the outer maxillipedes. 

 From the latter it is distinguished by the much greater rugosity 

 of the antero-lateral portions of the carapace, by the more 

 strongly arched and better defined antero-lateral borders, by the 

 narrower epigastric crests and by the deep groove which separates 

 them from the postorbitals. In P. annandalei the post-orbital 

 crests are continued sharply and uninterruptedly to the blunt 

 epibranchial tooth, whereas in P. decourcyi they are broken up 

 into tubercles external to the point where the cervical groove 

 would, had it existed, have cut them. The epibranchial tooth 

 is moreover much sharper in the present species. 



The large male specimen was obtained for me by Capt. the 

 Hon. M. W. R. de Courcy (Regd. no. ~, type) in the Sirpo valley 

 near Renging. The other examples were taken at Rotung (^), at a 

 point a few miles south of Kebang (^'), and on the banks of the 

 Siyom R. below Debuk Damda ('^). All were found under stones 

 in small hill streams at altitudes of between looo and 1500 ft. 



Potamon (Potamiscus) aborense, sp. nov. 

 (Plate xviii, figs. 4, 5.) 



This species differs conspicuously from the preceding and 

 from P. annandalei in that the post-orbital crests are not sharply 

 cut and prominent, but are merged to a great extent in the rugosi- 

 ties of the carapace. Its nearest allies are P. sikkimense, Rathbun, 

 and P. obliteratum , sp. nov. 



The length of the carapace is about five-sixths its greatest 

 V)readth and the depth is about half the breadth. The carapace 

 is much more convex fore and aft than in P. sikkimense and is 

 slightly but decidedly convex from side to side. The anterior and 

 antero-lateral parts of the carapace are very strongly rugose (fig. 

 4), the whole dorsal surface is pitted and there are well-marked 

 oblique striae on the side-walls which pass across the postero- 

 lateral borders. 



The cervical groove is distinct where it defines the mesogastric 

 area, but thence onwards to the post-orbital crests is obsolete, its 

 course being only discerned with the greatest difficulty. 



The epigastric and post-orbital crests, as in P. sikkimense, are 

 not distinctly separated from one another and form a common 

 curve. The crests are not sharp and salient but are to a great 

 extent merged in the large and conspicuous rugosities of the an- 

 terior part of the carapace, this is more particularly the case with 

 the post-orbitals. The position of the epibranchial tooth is marked 

 by a strong blunt angular lobe (fig, 4) of a far more evident 

 nature than in P. sikkimense (fig. 8) — a lobe the prominence of 

 which is greatly emphasized by the large gap which separates it 

 from the outer orbital angle. In P. sikkitnense, moreover, the post- 



