i, a Aco ee 
52 
a little hook a short distance away from the edge of the shell. 
The interior is dark brown, with a white deck. The edge of 
the deck is straighter than in the other two species, and it is 
not notched at the left end. When C. glauca grows on a flat 
surface it is like this; but when it 
grows upon a small shell or pebble, 
it becomes very deep, very convex, 
the deck concave ; but still the edge 
of the deck has the same form. C. gtanea. 
Z* This convex form of C. glauca is Saar 
called variety convera Say. They vary from dark to light or 
Crepiduliglausy 
mottled in color. 
The Naticide or Moon 
Shell family have the 
appearance and organ- 
ization of the plant-eat- 
ing snails, but for all 
that, they have carniy- 
orous habits. Their 
shells are globular, the Y 
aperture half-moon 
shaped, and closed by a 
thin plate or opercu- 
lum. The fleshy part 
of the animal is very 
large. Naticide live Fig. 44..Natica dapltestis 
on sandy beaches, where they burrow along a little way 
below the surface, in search of bivalve mollusks upon 
which they feed. A peculiar little hillock, which one soon 
learns to recognize, shows where a Natica may be found under 
the sand. ‘ 
