NUDIBRANCHIATA OF THE L.M.B.C. DISTRICT. 161 
branchs. Our nudibranchs were all alive, healthy, and 
good-sized specimens; and our fish were probably the 
right kind, being nearly all shore fishes, found in the im- 
mediate neighbourhood of where the nudibranchs live. 
But still the conditions were, of course, to a certain extent 
artificial, and that must be taken into account in drawing 
conclusions. Dropping the nudibranchs into the tank 
from above is unnatural, and may give rise to a mislead- 
ing result, especially where the fish are accustomed to 
have their food thrown in from above, and only receive 
edible food. 
Then again, at least some of the fish—those that have 
been some time in captivity, have been educated to com- 
pete with one another for the food masses. When anything 
is thrown in—a bit of white shell will do—there is at 
once a rush made upon the falling object, and no time is 
allowed for inspection or consideration. I would account 
for the seizing of Molis by the shannies (very active, vora- 
cious, and apparently impulsive fishes), even when the 
prey is evidently distasteful and has brilliant warning 
colours, as a result of this acquired habit of competition, 
and of pouncing upon anything thrown into the tank; 
several times when a morsel was suddenly bolted, it 
seemed to be because another fish was coming up to seize 
it. Still there is a marked difference between the man- 
ner in which they take a cockle and, say, an Ancula. The 
cockle is taken right in and swallowed at once, while the 
distasteful nudibranch, even if seized, 1s usually only 
partly taken into the mouth, in some cases it is seen to 
be held by the very front of the jaws, and is then ejected 
with force. 
Ancula has been a particularly interesting case. Start- 
ing with the general opinion that Ancula is a perfectly 
defenceless sott-bodied animal, we were astonished to find 
