420 ‘ Journal of the Asiatic Society of Bengal. [N.S., XIX, 
cus in the centre of the lower surface, with 34 whorls. The 
periphery of the body-whorl is.subcarinate and there is a dis- 
tinct angle or low carina on the outer part of the whorl above. 
The suture is broadly impressed, oblique and irregular, The 
mouth is very broad and shallow, narrowly oval, strongly 
depressed and oblique, extending far below and beyond the 
remainder of the shell, with the peristome complete and angu- 
late internally, but without a strongly developed calius The 
outer lip isconvex and sharp, without any internal thickening. 
The sculpture consists of moderately well developed, fairly 

Fig. 4 Type-specimen of Gyraulus longios, sp. nov. 
a vertical striae and numerous extremely minute spiral 
stri The colour is pale horny, but there is a thin greyish 
depos on the shell exam nd Max. diam., 45 mm.: min. 
diam., 4:2 mm. : height mn 
Locality. clit ahiows the Upper Mekong. 
Altitude. 6,400 f secs ih ol peal br ; 
Type- sepbitionett No. M. 22497 2. S1. (Ind. Mus.). 
The specimens from Sanda. doubtfully referred by Nevill 
to G. compressus Hutton (= euphraticus Mousson) probably 
