444 Journal of the Asiatic Society of Bengal. [N.S., XTX, 
ill-defined longitudinal rows of tubercles. The movable finger 
has 3 or 4 dorsal tubercles at the proximal end. Both fingers 
bear longitudinal rows of pits and have small teeth on their 
inner edges. The fingers do not gape appreciably when the 
claw is closed. 
e second pair of walking legs is the longest and is 
rather less than twice the length of the carapace. In all four 
pairs the upper edge of the merus is rugose and both borders 
of the propodite spinulose. The dactylus throughout is longer 
than the propodus and the latter segment in the last pair is 
18 times as long as broad. 
The species is described from a single adult male having 
the following measurements (in mm.) :— , 
Length 22°5 
Breadth 27°5 
Depth & és 13:0 
Fronto-orbital breadth .. Pee 193 
Distance between epibranchial teeth 23'3 
Breadth of mesogastric areola re Hel 
The specimen was obtained from the river at Yung-chang, 
in the Mekong watershed, at an altitude of about 5,500 feet. It 
was collected on 23rd May, 1912, from a pool in a stream out- 
side the city wall. Yung-chang is a large city, about six days 
march south of Tali-fu, situated approximately in Lat. 24° 
27’ N., Long. 100° 10’ E. It is preserved in the Indian 
Museum under the number C 792/1. 
The nearest ally of this species appears to be Polamon 
(Potamiscus) tumidulum Alcock ' from Sikkim. On comparison 
this species differs in the following points: (i) the areolation 
of the carapace is better defined, the cervical groove in parti- 
cular being well marked throughout its coarse; (ii) there is a 
conspicuous curved groove behind each epigastric crest, defin- 
ing an epigastric areola (these are well shown in Alcock’s 
figure) ; (iii) the mesogastric areola is proportionately broader ; 
(iv) the upper orbital margins are transverse ; (v) the antero- 
lateral margins are less strongly arched and less crisply serru- 
late, and (vi) the chelipeds are smoother. 
_ Potamon (Potamiscus) alcockianum Kemp * from Northern 
Siam is in some respects similar, but the carapace is much 
flatter and shallower and is very strongly rugulose anteriorly. 
The mesogastric areola also is broader and the front is densely 
tuberculate. 
Paratelphusa (Phricotelphusa) elegans (de Man). 
1910. Paratelphusa (Phricotelphusa) elegans, Alcock, Cat. Ind. Decap. 
Crust. I, fase. ii, Potamonidae, p. 104, Plate XIII, fig. 63. 


: Alcock, foc. cit., pp. 43, 58, Plate II, fig. 6. 
Kemp, Journ. Nat. Hist. Soc. Siam, VI, p. 24, Plate III. fig. 7 (1923). 
