Naticidae and Lamellariidae 125 



tinted; a dark presutural band about first few whorls; surface smooth, 

 fine growth lines; thin, glossy periostracum; aperture semilunar, 

 outer lip sharp, protracted above; columella oblique; umbilicus deep, 

 partly closed by dark-colored callus; interior of aperture usually 

 dark-colored, lustrous; operculum corneous, dark-amber color. 

 Found with A'^. canrena up to about three fathoms. 



Genus SINUM Roding, 1798 

 Sinum perspectiyiim--!^ (Say) PI. 24, fig. 168 



Shell auriform, depressed to altitude of a few millimeters; 

 greatest diameter of base approximates 35 millimeters; apex and 

 spire flattened to plane of body whorl; color milk-white; thin, yel- 

 lowish, papery epidermis; about three whorls; sutures faintly im- 

 pressed; surface sculpture of numerous well-engraved, subequidistant, 

 revolving, slightly wavy lines and fine longitudinal lines of growth; 

 aperture wide, rounded; outer lip sharp, finely crenulate; operculum 

 corneous, minute. 



In the living animal, only a small portion of the upper surface 

 of the shell is exposed. 



Sandy bottom in shallow water. 

 Sinum maculatnm-^s (Say) PI. 47, figs. 325a, b 



Shell a little smaller and less depressed than S. perspectivum, 

 with two maculated bands of chestnut-brown about the upper whorls. 



Family LAMELLARIIDAE 



The mollusks which constitute this family bear shells which 

 are similar in general characters to those of the genus Sinutn, but 

 much smaller, more delicate in structure, and without an operculum. 

 The shells are almost or wholly covered by a reflection of the mantle. 



The animals are carnivorous and are usually found in associa- 

 tion with compound ascidians, Hydrozoa and Alcyonaria; their eggs 

 are deposited among the folds and in the crevices of colonies of these 

 animals. Some of them are brightly colored and their general ap- 

 pearance is usually more suggestive of a nudibranch or a platyhel- 



221 Lat., sinus, a bend or hollow; perspccti'vus, perspicere, to look through. 



222 Lat., maculatus, spotted. 



