148 TECTIBRANCHIATA.—BULLADA. 
is so open as to display the whole interior even to 
the summit. 
The Gaping Bulla is common on our coasts, es- 
pecially in the south, inhabiting muddy and sandy 
ground at afew fathoms’ depth. I have dredged 
it abundantly in Weymouth Bay, a mile or two 
from shore. In captivity it is sluggish, remaining 
inert at the bottom of the vessel in which it is kept, 
so as to be an uninteresting subject of observation ; 
added to this it continually secretes and discharges 
a viscid slime, which stretches through the water 
in long tenacious strings, and envelopes and dis- 
tresses any other marine animals which may be its 
fellow-captives. Some of the Nudibranchs discharge 
mucus in the same manner; but I know of none 
that possesses the disagreeable quality to the same 
extent as this Bulla. 
