XX. CRUSTACEA DECAPODA. 



By vStanley Kemp, B.A., Assistant Supenntendent, 

 Indian Museum. 



(Plates xvii — xxi.) 



In the present report twelve different forms of Decapod Crus- 

 taceans are recorded, viz.: — 



Potamon {Potamiscus) decourcyi, sp. nov. 

 ,, aborense, sp. nov. 



,, ohliteratum, sp. nov. 



(Geotelphusa) adiatretum, Alcock. 



,, ,, var. lophocarpus , nov. 



,, superciliosum , sp. nov. 



[Acanthoteiphusa) jeae, de Man. 

 ParatelpJmsa {Barytelphu>a) harpax, Alcock. 

 Palacmon hendersoni, de Man. 

 Caridina weberi, de Man, var. 

 ,, excavata, sp. nov. 



,, Jiodgarti, sp. nov. 



One of the species, Potamon {Potamiscus) obliteratuniy was 

 found by Mr. F. H. Gravely in the Dawna Hills on the Burmo- 

 Siamese frontier, and is included here in order to render more com- 

 plete the account of the subgenus to which it belongs. Of the 

 remainder, six are to be regarded as true hill forms, having been 

 found in the small mountain streams draining into the Dihang river, 

 while five, Potamon (Acanthoteiphusa) feae, Paratelphusa {Bary- 

 telphusa) harpax and the three species of Caridina were found at 

 the base of the hills and in the Brahmaputra valley. 



No less than seven of the eleven Abor forms appear to have 

 been undescribed hitherto, and the collection is, in consequence, 

 of but little assistance in determining the geographical relation- 

 ships of the fauna. 



The subgenus Potamiscus, as far as is at present known, 

 extends from Rajputana, Nepal and Darjiling to Burma and has 

 been found at Cachar in Assam, while Potamon [Geotelphusa] 

 adiatretum has been recorded from the Dafla country, from the 

 Khakyen Hills and from Moulmein. Potamon [Acanthoteiphusa) 

 feae, described from the Upper Irrawaddy, seems to be not uncom- 

 mon in Assam north of the Brahmaputra, and Paratelphusa 

 {Bary telphusa) harpax is a species of wide distribution in north- 



