194 
protoconch its previous site is closed by a sunken lamina with 
subdistant erect transverse lamellx, convex posteriorly. Be- 
tween it and the anterior margin is a differentiated rib, 
broader and higher than the rest, fissured superficially 
throughout. In its upper part the fissure is as wide as the 
perforation, but is nearly closed internally by horizontal 
laminze from the sides. It gradually contracts anteriorly 
to a fine line; in its upper half the fissure communicates with 
the interior, in the lower it is shut off. The slit fasciole and 
perforation are bounded on each side by a delicate erect lam- 
ina, highest at the perforation, in front of which the lamins 
gradually approximate to form the differentiated rib. From 
the protoconch to the margin this lies a little to the right of 
the actual median line of the shell. Sculpture: Radial ribs, 
well rounded, nearly smooth, about as wide as their inter- 
spaces, sixteen primary, but increasing rapidly by intercala- 
tion of secondary and tertiary riblets to 90 in a shell of 10 
mm. length, and crenulating the margin. These riblets ap- 
pear first as gradually enlarging tubercles in the centre of 
the intercostal spaces, situated on the concentric lamine, 
which conspicuously cross the interspaces, slightly scale the 
bases of the ribs, but are barely visible under the microscope 
on their summits. They produce radial lines of punctations 
in the interspaces, and in old dead specimens, where the glaze 
disappears from the interior, these appear as perforations. 
The ribs posteriorly are broader and closer together. Inter- 
nally a small shelf or septum convex towards the interior, with 
a sharp simple margin anteriorly hides the upper fourth of 
the perforation, being attached to the shell at a distance from 
the margins of the perforation about equal to the width of 
the perforation; it gets gradually narrower and less obvious 
posteriorly. Its dorsal surface slopes up to the slit fasciole, 
the last one or two scales of which roof in the back of its 
cavity. From the perforation anteriorly runs a gutter to 
the margin; in older examples this becomes a thin central 
ridge. Shallow radial furrows correspond with the external 
ribs. As individuals get older, the shell grows more rapidly 
posteriorly, so that the apex gets less eccentric, and the back 
part becomes very flat and sloping. 
Dim.—When half-grown, length, 10 mm.; width, 8 mm. ; 
height, 1'4 mm. ; apex, 1°8 mm. from the posterior end. When 
full-grown, length, 18 mm.; width, 154 mm.; height, 4°7 mm. ; 
apex, 54 mm. from the posterior end. 
Locality.—130 fathoms, off Cape Jaffa, 20 whole or 
broken ; 300 fathoms, 4, all dead. 
Obs.—The shell appears to fall within the limits of 
Cranopsis. I have no shells of this genus with which to com- 
