390 MARINE INVERTEBRATES 
FAMILY NASSIDE 
These are familiar, and often very characteristic, littoral shells 
in all parts of the world. Where they exist at all they are gener- 
ally to be found in astonishingly large numbers, sometimes even 
crowding out all other mollusks. They are exceedingly active 
and predaceous, feeding upon other mollusks, whose shells they 
bore through by means of the sharp teeth upon their lingual 
ribbon. The Nassidw of the east coast find a relentless enemy 
in the small hermit-crabs, which attack them, drag them from 
their coverings, and then proceed to occupy the empty shells 
themselves; the torn and lacerated Nassa animal is thereupon 
leisurely eaten, a retribution probably well deserved. The animal 
of Nassa (the principal genus of Nassidw) is peculiar in having 
frequently a bifurcated tail; or, to speak more correctly, the 
posterior end of the foot is terminated by two appendices. 
It has a long siphon, and eyes placed upon the outer sides and 
near the base of the tentacles. The operculum has serrated 
edges. 
Genus Nassa 
N. trivittata, N. obsoleta. These are the two nassas of the New 
England and New Jersey coasts. The first has a more northerly range, 
extending to the Gulf of 
St. Lawrence ; the other is 
not usually found north 
of Cape Cod, but below 
that point as far as Hat- 
teras it is probably the 
commonest shell of the 
coast. It fairly swarms in 
: sheltered muddy reaches 
about low tide. Little pools left by the tide on the Jersey 
flats are sometimes so crowded with N. obsoleta that for lack 
of room the animals crawl over one another. N. trivittata is 
more commonly taken at small depths in the harbors, where 
it seems to live well upon all kinds of sea-bottom. Probably { 
they exist in great numbers along the southern shore of Long 
Island, for the beaches are often lined with their dead and 
worn shells. Over half the specimens thus found will have a ‘ 
little round perforation upon some whorl, showing that they ee iy 
were victims of some cannibalistic brother. The shells of the ‘ 
Nasside have a short, ovate aperture, with a short anterior canal. The 
inner lip is smooth, and is usually coated over with a more or less heavy 
Nassa trivittata, showing the animal as if crawling. 
