20 
riorly, and slightly dilated at the base ; columella with a light fold, 
white and shining. 
Animal.—Cephalic disc large, oblong triangular, entire in front 
and truncated, bilobed posteriorly and lobes overlapping; lateral 
lobes reflected on the sides of the shell during locomotion, covering 
about one-half of its length, and nearly meeting on the back ; poste- 
rior lobe covering the spire; foot subquadrate, extending a short 
distance beyond the shell posteriorly ; eyes central, immersed, black, 
surrounded by white areolz ; colour of the animal varying from grey 
to greyish-yellow, and in some nearly to black, being closely mottled 
and freckled with olive or dusky. 
Mus. Cuming. 
Found usually on sand-flats, but occasionally met with on sea- 
weed. They are most abundant on the leeward island of our group, 
from whence they become less common towards the windward, being 
very rarely met with on the windward island. 
5. HAMINEA PUSILLA. 
Shell small, cylindrically ovate, rather solid, white, surface finely 
cancellated ; apex slightly umbilicated or perforated ; aperture nar- 
row, contracted posteriorly ; slight fold at base of columella. 
Mus. Cuming. 
6. ATYS SEMISTRIATA. 
Shell oval, contracted posteriorly, thin, fragile, pellucid, white, 
transverse raised lines at both ends ; aperture slightly dilated at the 
base ; apex perforate. 
Mus. Cuming. 
7. ATYS DEBILIS. 
Shell cylindrically ovate, elongate, narrowed posteriorly, pellucid, 
fragile, white ; outer lip produced and twisted posteriorly ; apex um- 
bilicated, and umbilicus striated or grooved, finely striated trans- 
versely, transverse raised lines at both ends; columella with a fold 
at the base. 
Mus. Cuming. 
Genus VOLVATELLA. 
Shell convolute, subpyriform ; aperture wide anteriorly, contracted 
posteriorly and produced, forming a circular aperture. 
Animal.—Mantle concealed ; cephalic dise quadrate; tentacular 
lobes produced from the corners ; anal aperture posterior ; foot small 
and triangular. 
8. VoOLVATELLA FRAGILIS. 
Shell thin, horny, subpyriform, convolute (finely striated longitu- 
dinally), covered with a membranaceous epidermis; spire none; 
aperture wide, dilated at the base and contracted posteriorly ; the 
lips thin and entire, meeting at about one-half the length of the shell 
