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agent; and the tribe of rock-fish, the blennies, gobies, &c. are also 
most voracious, devouring all the varieties of Cirrhipeds, corallines, 
Polyps, Annelids, &c.; they will also attack the shrimps and prawns, 
and even seize upon the horns of the periwinkle, which they bite off. 
Ifthe mollusks do not keep a very firm hold of the rock or tank sides, 
they are rapidly turned over by these fish on their backs and 
lie helplessly exposed to their attacks.* It is doubtless their seeking 
food of this kind which causes these little fish to be so generally found 
in the shallow rock-pools of the coast. Im consequence of these ra- 
venous propensities, | have been obliged to establish several small 
tanks and imitation rock-pools, so as to separate these various depre- 
dators from each other: thus in one I have varieties of Actinia, 
shrimps, Nudibranchs, Holothurias, and some Annelids ; in a second 
the rock-fish, as the blennies, gobies, Cottus, with crabs and Actinie ; 
in a third corallines, Annelids, Polyps, rock-borers, Sabelle, Serpule, 
Holothurias, and Actiniz. 
Another curious instance of loss I may detail which has quite 
recently occurred, and which may prove interesting ; it was in a small 
rock-pool containing blennies, gobies, crabs, &c. I had procured 
two live oysters for the purpose of feeding my numerous small fry in 
these vivaria, and one of these having proved ample for the purpose 
of one meal, the other was placed on the sandy bottom; on the second 
day after this the oyster was observed to have opened the valves of 
his shell to a great extent, which were afterwards seen closed, but a 
small Gobius niger, inhabiting the pool, could nowhere be seen. The 
day after this the oyster was opened for the general feeding, when, 
lo! within the shell was found the unfortunate Gobius, quite dead. 
Whether this little gentleman had been attracted within the trap by 
curiosity or the ciliary motion of the oyster, it is impossible with cer- 
tainty to say ; but that he must have seized on some sensitive part of 
the oyster is more than probable, so as to have caused such a rapid 
closing of the valves of the shell as could entrap so active a burglar. 
* Since the reading of this paper at Hull I have received a blenny of larger size, 
being about 33 inches in length, and although it has become so tame that it will allow 
itself to be touched by the hand and takes its food from the fingers, yet its destructive 
propensities are so great, that it very soon killed four small crabs; and to save three 
others, of rather a larger size, I have been obliged to remove the blenny to a rock- 
pool in association with his own species and a few Actinie. The only refuge the poor 
crabs had was to bury themselves in the sand, and whenever they attempted to move 
out of their refuge they were immediately pounced upon and only escaped by burrow-- 
ing rapidly again. 
