249 LAND AND FRESHWATER 
“Diam. maj. 14:0, minor 8:0 mm. 
ee O57, iron [0:32 sineh: 
“This shell was found at Hengdan Peak, North Cachar Hills, 
but I never obtained a living specimen. I have, however, figured 
the shell, with the hope that a description of the animal may some 
day follow.” 
The shell differs much from cacharica in form of apex and its 
solidity, but the animal is, I have no doubt, very similar in form. 
Subgenus Dexuanta, Godwin-Austen. 
Type D. beddomet, G.-A. 
Animal. In general form like Girasia hookeri of the Khasi Hills, 
the posterior portion of the body being about equal to the part of 
the mantle covering the shell. The dorsal and shell-lobes are all 
united in an oval mantle or shield, leaving only a minute orifice like 
a pinhole in the posterior median side; the shell is only shown to 
this extent in the contracted spirit-specimens, so that in life and 
fresh it must be completely hidden. From this small opening a 
distinct line or cicatrix runs towards the respiratory aperture on 
the right side, indicating that it is the remnant of a form, perhaps 
extinct, in which the shell-lobes were originally separated into 
right and left lobes. The whole mantle rests deeply below the ridge 
of the posterior portion of the foot, in a depression which is square 
behind, not V-shaped. The pedal groove or line is not so deep and 
well shown as in Girasia, and the segmented margin is narrower. 
The extremity of the foot is cut off square, the mucous pore being 
a narrow vertical slit, extending to the sole of the foot. 
The generative aperture is posterior to the right tentacle. 
The shell, Fhis is of an extremely solid, shelly character, oval in 
form, dextral, white, marked with close, concentric lines of growth, 
flatly convex above, flat and smooth beneath, its internal side is 
thus completely filled with shelly matter; apex solid. 
The generative organs are like those of Girasia, save that the 
amatorial organ is not so large. 
The odontophore (Plate LXII. figs. 7, 7 a) presents a considerable 
departure from Girasia, both in the shape and far greater number 
of the teeth inthe row. The centrals are broad and triangular, with 
small basal cusps ; the median evenly bicuspid, the lateral becoming 
very minute on the margin. 
The teeth are arranged as follows :— 
122) ..Os.° 20 jo Seo ee ba 120 
Lis". 1 448 
The jaw is solid, semicircular in form, with a slight projection on 
the concave cutting-edge. 
There seem to be many local varieties in the collection, differing 
in coloration only (just as Avion of our European area is seen to 
