1919.]| N. ANNANDALE & B. PrasHap: Gastropod Molluscs. 109 
Each whorl is nearer the inner than the outer margin of the one 
that succeeds it. They are slightly swollen and slightly flattened 
above. The apex is small and rounded. The body-whorl is long 
but rather narrow and not very convex. Its upper surface is 
flattened and oblique but not angulate. The inner margin is 
Z-shaped, the upper half of the outline consisting of a somewhat 
flat curve. It then slopes in fairly abruptly and finally forms a 
broad projecting lobe, which corresponds with the inner anterior 
angle of the mouth. This lobe does not project so far sideways 
as the outline of the upper part of the whorl. ‘The outer margin 
of the whorl forms an arc of wide diameter and less than a semi- 
circle. The surface is not highly polished. It is ornamented with 
rather coarse and irregular longitudinal ridges, some of which may 
be called low costae, and striae. Minute spiral striae are also 
‘present. ‘The first three whorls are, however, almost smooth. 
In ventral view the shell is ovoid. The body-whorl is swollen 
above and transverse at its upper margin. It disappears behind 
the mouth some little distance above the anterior extremity of the 
latter. The shell is very narrowly rimate. The mouth is long and 
somewhat expanded, ovate, nearly vertical, sometimes narrowly 
rounded or truncate both above and below, sometimes pointed above 
and rounded below. ‘lhe lip is thin and sharp and its curvature 
is often uneven but never highly convex. The callus is well 
developed above, joining the columellar border to the lip. The 
columella is long and twisted but not curved. The margin of the 
mouth is long, straight and vertical below the umbilicus. The 
columellar border is expanded and flattened over the umbilicus. 
The inner anterolateral border of the mouth is very slightly ex- 
panded and produced. The sculpture of the surface is not so 
well developed in this view as in the dorsal. 
As seen from above, the spire increases gradually but often 
irregularly and the suture becomes gradually more impressed until 
it is practically canaliculate as it approaches the outer lip. 
The radula has the dental formula 13.8.1.8.13. The central 
tooth though minute is distinctly bicuspid, having a small, 
sharp subsidiary cusp at the base of the main one, which is narrow 
and sharp. The laterals are tricuspid and their cusps are long, 
slender and sharply pointed. The lateral cusps are equal and a 
little smaller than the central one, but the inner cusp arises at a 
considerably lower level than the outer one. ‘The marginals are 
very uniform in structure. Each has three (or occasionally four) 
subequal cusps arranged in a slanting line. The only difference 
between those of the inner and the outer rows is that in the later 
the cusps are blunter and a little less regular in shape. 
The jaw is broad, dark and stout. The free margin of the 
upper part is broadly truncate and the internal surface is concave 
in the middle region. 
The animal, as seen in a highly contracted state and preserved 
in spirit, offers no particular external diagnostic features. The 
mantle is pale with large dark spots. 
