MARINE UNIVALVES 183 
name is derived. The use of the canal seems to be 
to afford space and protection for a breathing 
tube which projects above the surface of the mud 
which the animal is exploring for his prey. 
The Nassas are active mollusks, and are cordi- 
ally hated by the oystermen, because they are so 
fond of boring a hole through the shells of young 
oysters, and eating the contents with as much 
relish as any other Judge of good living. They bore 
into various clams, too, and it is even hinted that 
they sometimes attack their own kind. But they 
are scavengers also, and consume the flesh of dead 
erabs and like animals, which are so hable to be 
found near the shore. In turn they are themselves 
eaten, for I have some beautiful specimens of this 
species which were taken from the stomach of a 
large fish, showing that the biter of other animals 
is hable to be swallowed whole when the avenging 
and hungry fish comes around. The length of this 
shell is seldom as much as two inches. 
Nassa tégula, Rve., the Covered-lip 
Nassa, Figure 184, is a southern spe- 
cies, having a strong shell, a small 
aperture, and a reflexed canal. ‘The 
inner lip is covered with a large callus 
of smooth, white enamel. The color is 
Bigs dark gray and the length is_ three- 
fourths of an inch. 
