between Animal and Vegetable Organisms. 4121 



a beautiful little pipe-fish [Syngnathus lumbriciformis) , and several 

 others, and on opening the door of the case the cause of this mor- 

 tality was at once evident, — an iridescent film of oily matter was float- 

 ing on the surface of the water, arising from the paint with which the 

 angular joints and edges of the small tank had been coloured not 

 having become sufficiently hardened. 



Another source of loss arises from the several creatures attacking 

 and devouring each other, and it therefore becomes a point of great 

 importance — and highly necessary to be carefully observed, where 

 their preservation is an object — to ascertain what varieties may 

 be safely associated in the same tank ; as, for instance, I have found 

 that the shrimps and prawns attack, and very soon devour, all 

 the larger varieties of corallines and Polyps, Sabellae, Serpulae, rock- 

 borers, Cirrhipeds, some of the Annelids, many bivalve and univalve 

 mollusks that are unprotected by an operculum, or have no power of 

 closing their valves. The instances which have come under my own 

 immediate observation have been the destruction of the Pholas dacty- 

 lus, Saxicava rugosa, Cypraea Europaea, and several specimens of 

 Sabellae, Serpulae, Coryne sessilis, and many others. 



The common crab {Cancer Manas) is likewise a most destructive 

 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. 

 If the 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. In consequence of these ra- 

 venous propensities, I 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, 



* Since the reading of this paper at Hull I have received a blenny of larger size, 

 being about 3k 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 Actinia;. 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. 



XI. 3 F 



