213 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol. VIII. 
exhibited of keeping on doing nothing ; for instance Planazis sulcatus 
is a common little black shell, living on rocks at about 2 tide mark, 
and he ought to be pretty hardy, considering the amount of heating he 
can stand at one time of the year and drenching with fresh water at 
another ; but in confinement I could make nothing of him. He would 
not condescend to stop in my tank, notwithstanding daily supplies of 
fresh salt water, syringings to aérate it, and surroundings in the shape 
of slimy stones, such as must have been familiar to him. He pre- 
ferred, however, an adjoining deal box, on which he had climbed, and 
there he sat and brooded over his misfortunes till I returned him to 
his element as hopeless. 
The univalves are both vegetable feeders and carnivorous, and they 
are armed witha long rasping tongue, composed of microscopically 
minute calcareous teeth. This tongue, in the case of the carnivori, and, 
as is thought by some authorities, with the aid of an acid they have the 
power of secreting, enables them to bore holes in the shells of bivalves 
and other members of their own species. An actual case of this boring 
happened under my own observation—a specimen of Urosalpinz 
contracta perforating the shell of Semele cordzformis (a bivalve) in about 
twenty-four hours. 
The Semeée had, as is the custom of most bivalves, embedded itself in 
some sand provided in my tank for that purpose, and how Urosalpinex 
got him on to the top of the sand I can only surmise ; but it was there 
that the boring operation took place. 
This custom of retreating into the sand is no absolute protection 
to the bivalves from their enemies the univalves, as many of the latter 
regularly burrow in search of them, which is attested by the large 
quantity of bivalve shells found with a circular hole drilled through 
them. The animals of the Natica family, four to five of which are very 
common here, are specially adapted for this burrowing. They have a 
large and powerful foot or gliding surface ; they are blind or nearly so, 
and are provided in front of the head region with a sort of shield, 
Their shell is light, very smooth and round, and so offers little or no 
resistance to the pushings through the sand ; but Urosalpinex belongs to 
a family differing widely from this description. Most members of it are 
heavy shell-bearers, and their shells are rough and ridged, often with 
varices or fringes, and they frequent, as a rule, rocks or:muddy stones, 
