294 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 
Cancellariidae. 
CANCELLARIA Lamarck. 
Type Voluta reticulata Linné. 
Narona H. anp A. ADAms. 
Type C. mitraeformis Sowerby, not Brocchi. 
Cancellaria (Narona) exopleura Datt, n. sp. 
Shell small, slender, acute, with five rounded whorls, a deep suture, a pilose 
periostracum, whitish more or less banded spirally with reddish brown; nucleus 
defective, but apparently glassy, bluntly pointed and with about two whorls ; 
subsequent whorls with (on the antepenultimate whorl fourteen) narrow, sharp, 
low riblets, with wider interspaces, becoming relatively less prominent on the later 
whorls; these are crossed by from four to six narrow, subequal, distant, rounded 
spiral threads, not nodulous at the intersections; the last whorl is also furnished 
with two or three prominent varices, irregularly disposed, beside the terminal 
varix; these are thick and rounded; on the last whorl there are about fifteen 
feeble spirals and some intercalary finer threads appear; aperture slightly shorter 
than the spire, semilunate, the outer lip reflected and thickened, with 9-10 denti- 
cles internally, not. continued into the throat; inner lip not callous; pillar with 
two strong distant plaits, the canal wide, produced and recurved; no operculum. 
Length of shell, 26; of the last whorl 18; of the aperture, 12.5; max. lat. 12 mm. 
U. S. 8. * Albatross,” station 2804, in Panama Bay, in 47 fathoms, muddy 
bottom. U.S. N. Mus. 96,638. Also at Payta, Peru, Dr. Jones. 
This is nearest to C. clavatula Sowerby, from the same region, which is a 
smaller shell, with one less whorl, with fewer ribs (ten on the antepenultimate 
whorl), which are rounded and much more prominent; the whorls in C. clavatula 
also increase more rapidly and have a tabulate aspect. 
Cancellaria (Merica) corbicula Datt, n. sp. 
Plate 1, figure 4. 
Shell small, thin, milk-white, with a thin, pale yellow periostracum, and about 
six whorls beside the blunt (decollate) nucleus; form bulimoid, aperture nearly 
equal to the spire in length; whorls evenly rounded, with a strongly marked 
suture ; sculpture between the sutures of seven to nine flattish revolving threads 
with slightly wider channelled interspaces; these are crossed by numerous, sub- 
equally spaced, very narrow, low, slightly arcuate axial ridges, slightly nodulous 
at the intersections ; there are also very numerous, prominent, incremental lines 
in the interspaces; aperture oval, outer lip thin, smooth, entire, reflected; inner 
