TOP - SHELLS. 
33 
Calliostoma canaliculatum , Mart., Grooved 
Top-shell, Fig. 4, PI. YI1T, is upwards of an inch 
in length and breadth. It is very thin and light, 
conical in shape, and marked by very strong spi- 
ral lines alternating with lesser ones, with a dis- 
tinct suture between the five whorls. Exterior 
color, light brown ; interior of aperture, brightly 
iridescent. 
Trochiscus Norrisii , Sby., Fig. 5, PI. VIII, 
abundant southward, rare at Monterey, is a large, 
smooth, brownish shell, with low spire, rounded 
whorls, very large umbilicus, and ample aperture, 
which is closed by a mossy, circular operculum. 
It is found on the rocks, like the Turbans. The 
The last shell, No. 7, figured on plate VIII, is 
Leptonyx sanguineus , Linn., alias Leptothyra 
sanguinea . The figure shows the natural size, 
though it sometimes grows larger. It is strong 
and solid, few whorled, marked by regular spiral 
striae. It may be distinguished from small spec- 
imens of C. costatum, by its rounded whorls, 
white interior, and white, shelly operculum. Its 
color is red or purple. It may be found living 
on the surface of rocks, at low water. 
