GASTEROPODS 369 
Genus Sigaretus 
A very interesting species of this genus occurs on the east 
coast, sparingly in New Jersey, but very abundantly south of 
Hatteras. Sigaretus is a modified Natica. The spire is flattened 
and minute. The body-whorl, being greatly expanded, gives a 
wide, flaring, oblique aperture. The shell is ear-shaped and white, 
with fine revolving lines. There isno umbilicus. The operculum 
is small and rudimentary. The animal is large, with an enormous 
foot and greatly developed propodium, and is a sand-dweller. 
The common east-coast form is S. perspectivus. (Plate LXVIII.)’ 
FAMILY CAPULIDE 
Genus Crepidula 
C. fornicata. All collectors of mollusks on the Atlantic coast sooner 
or later encounter this exceedingly common species adhering to oyster- 
shells or scallops, and often to other large live shells. 
It is cast upon the beach along the entire length 
of the Atlantic coast. The shell is obliquely oval, 
dull whitish in color, and either smooth or rough 
or even ribbed, according to the nature of the sur- 
face to which it clings. The spire is almost entirely 
suppressed, the little inconspicuous apex being 
turned to one side and closely pressed down against 
the body of the shell. When looking into the in- 
terior of the shell one is reminded of a boat, for the 
upper portion of the aperture is covered by a 
horizontal shelly partition, called the diaphragm, 
a space being left below which would correspond 
to the forecastle of a ship. The “stern” is round, 
and the “bow” is suggestively pointed. 
C. plana. In this species the shell is white and flat, 
or slightly concave. Although it is pointed at the ‘‘ bow” 
end and square at the “ stern,” the nautical resemblance 
stops there, because, being flat, there are no swelling 
sides and bow. The diaphragm is about one half the 
length of the shell, convex, shining, white, and trans- 
lucent. C. plana lives generally within the aperture of 
large dead shells. It has a wide range, from Maine to 
Crepidula plana. Florida. 
C. aculeata. A common Floridian species which has 
a remarkable range, being found in nearly all the tropical and semi- 
tropical waters of the world. It is smaller than C. fornicata, 1s reddish- 
brown with a white diaphragm, and has several radiating ribs on the 
back, which are inclined to be nodulous. (Plate LX VIII.) 
a4 
Crepidula fornicata, 
