98 LAND AND FRESHWATER 
Locality. Calcutta. 
Shell very depressedly conoid, base flat, thin, translucent, shiny ; 
sculpture longitudinal, the bands rather waved, the transverse lines 
of growth not very distinct (Plate XXI. fig. 1); colour pale umber- 
brown ; spire low, sides flat, apex convex; whorls 54, regularly 
increasing, flat above, the last rounded; aperture subvertical, sub- 
globosely lunate; peristome thin, straight, the columellar margin 
obliquely descending. 
Size: maj. diam. 17-0, min. 14°8 ; alt. axis 6:3, body-whorl 5-8 mm 
SS OG cei 0-08 iets MO Hee ek 0-23 inch. 
Two other specimens :— 
Maj. diam. 18-7, min. 16°3; alt. axis 8°3, body-whorl 6-7 mm. 
$s 0:74, 3° 0:643\%,,. 07338, - 0-26 inch. 
" LORS 7 eeU Sl Oren Te 8-75, ms “ 73 mm. 
Orin nt Or 71; 3». 0°35, 0-27 inch. 
The manile (Plate XVII. fig. 2, and Plate XXV. figs. 9, 10). 
The right shell-lobe small, the left is narrowly reflected over the 
edge oF the peristome, and at the basal side gives off a short tongue- 
like process ; the right dorsal lobe is narrow, elongate, and extends 
to the columellar margin near the great retractor muscles; the left | 
dorsal lobe has two distinct positions, as viewed from the outside 
(Plate XXY. fig. 10), an anterior and a posterior, but when turned 
back and viewed from below (fig. 9) they are seen to be united by 
a reentering concavity in the margin, which is not so free as the 
above portions on either side—an approach to the more distinct 
separation of the two portions which we find in MW. atricolor and 
other species (vide Plate XXYV. fig. 8). 
Generative organs. At the junction of the vas deferens a mode- 
rately long, cylindrical, blunt kale-sac is given off a short flagellum ; 
it is then straight for a short distance, forms a sharp twist, and is 
continuous again, but before reaching the retractor-muscle attach- 
ment it makes a close coil on itself, very typical of the organ in 
this and allied genera, of which a comparison may be made with 
the similar coil in MW. hardwicket (Plate XXVIII. figs. la, 14, 
Plate XXXII. fig. 56, &c.); from this it is straight and cylin- 
drical to the generative aperture. 
The amatorial organ is present as a large gradually tapering 
cylinder, with a retractor muscle at the posterior end. The sper- 
matheca is short and elongately pear-shaped. 
Odontophore. The jaw is moderately concave on the cutting-edge, 
with a well-marked central convex projection. The dental formula 
referred to on p. 85 is 
BA efit wD. 6 when) Qasra gaan: 
45.1. 45 
(88 rows counted). 
The central tooth is eclongately triangular, with two short pointed 
cusps on either side at about half the length. The median are 
similar, tricuspid, the inner cusp being higher, or about midway 
