MONOGRAPH OF THE GENUS STROPHIA. 
15 
The top-shaped form mentioned is very rare and is probably the 
results of an injury that the animal received, causing it to form a mar- 
gin to the shell when it was not fully grown. 
Distinguished from S. pannosa by the smaller size, thinner shell 
and margin, and more open aperture; from copia, which it resembles in 
size, by the smaller number of striations, 16 to 19 instead of 22 or more. 
The interspaces in this species are wider than the elevated striations, 
while in copia the reverse is the case. 
Known from all other species by the rather small size, elongated 
teeth, irregular, w T idely separated, coarse striations, and white color. 
DISTRIBUTION AND HABITS. 
The Small Rough Strophia is found on the coast of the south side of 
Little Cayman, west of a large mangrove swamp that nearly divides the 
island into two unequal portions, and along the beach on the south side 
of Cayman Brae, as far east as the cocoa-nut grove extends, now about 
half the length of the key. 
They are much more common than the Ragged Strophia, and al- 
though they mingle occasionally with the colonies of the Common Stro- 
phia that border the shore, they are never found far from the beaches. 
They are more common on Little Cayman than on Cayman Brae; see 
further remarks under habits of S. copia. 
4. STROPHIA ACUTA Novo. 
Pointed Strophia. 
Plate II, 4 & 4b, shell. 
DESCRIPTION. 
Sp. Ch. Size, rather small. Shell, moderately heavy. Striations, 
absent. Tentacles, not very short, about one third as long as the eye 
peduncles. Examined 500 specimens. 
Form of shell, pointed oval, the greatest diameter being at the su- 
ture between the first and second whirls, and each whirl below the sec- 
ond is successively .05 smaller than the one above it, and thus the shell 
tapers quite rapidly to the apex, forming an angle of about 46 degrees. 
There are only faintly defined lines of growth, that assume but little 
prominence even on the upper whirl; hence the shell is very smooth, and 
even the sutures between the whirls are very shallow. 
The aperture is small but rather open, the internal diameter, just 
inside the margin, being a trifle more than at the entrance. The lower 
