323 Mr. R. Waringtoii on Preserving the Balance between 



ing and devouring each other, and it therefore becomes a point 

 of great importance — and highly necessary to be carefully ob- 

 ser\ ed, where their preservation is an object — to ascertain what 

 varieties may be safely associated in the same tank ; as, for in- 

 stance, I have found that the Shrimps and Prawns attack, and 

 very soon devour, all the larger varieties of Corallines and Polyps, 

 Sabellae, Serpulse, 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 in- 

 stances which have come under my own immediate observation 

 have been the destruction of the Pholas dactylus, Saxicava rugosa, 

 Cypreea Europcea, and several specimens of Sabellse, Serpulse, 

 Coryne sessilis and many others. 



The common Crab {Cancer Mcenas) is likewise a most de- 

 structive agent ; and the tribe of rock-fish, the Blennies, Gobies, 

 &c. are also most voracious, devouring all the varieties of Cirrhi- 

 peds, Corallines, Polyps, Annelids, &c. ; they will also attack 

 the shrimps and prawns, and even seize upon the horns of the 

 periwinkle, which they bite. If the mollusks do not keep a very 

 firm hold of the rock or tank sides, they ai*e 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 iish to be so generally found in the shallow 

 rock-pools of the coast. In consequence of these ravenous pi'o- 

 pensities I have been obliged to establish several small tanks and 

 imitation rock-pools, so as to separate these various depredators 

 from each other : thus in one I have varieties oi Actinia, Shrimps, 

 Nudibranchs, Holothurias, and some Annelids ; in a second the 

 rock-fish, as the Blennies, Gobies, Cottus, with Crabs and 

 Actinia ; in a third Corallines, Annelids, Polyps, Rock-borers, 

 Sabellae, Serpulse, Holothurias, and Actiniee. 



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 nume- 

 rous small fry in these vivaria, and one of these having proved 

 ample for the purpose of one meal, the other was placed on the 



* Since the reading of this paper at Hull I have received a Blenny of 

 larger size, being about '6^ 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 obhged to remove the Blenny to a rock-pool in asso- 

 ciation with his own s})ecies and a few Actinia;. The only refuge the ])<)or 

 Crabs had vvas to bury themselves in the sand, and whenever they attemjited 

 to move out of their refuge they were immediately pounced upon and only 

 escaped by burrowing rapidly again. 



