270 J. G. WALLER ON THE BURROWING SPONGE. 



Professor Owen's " Palaeontology, "and in numerous other works of a 

 less scientific value, such as " Recreative Science," &c. In fact, with 

 the single exception of Dr. Bowerbank, I know of no one writing 

 upon sponges who does not still continue to speak of a " boring 

 sponge." To those who have no experience in the growth of these 

 organisms the proposition may not involve any great difficulty. I 

 have, therefore, thought it a proper subject for discussion in our 

 Society ; first, as a duty we owe to each other, to give the result 

 of our observations ; secondly, because, besides supporting Dr. 

 Bowerbank's views, I shall be able to add facts on the physiology 

 of the sponge, which do not appear to have fallen under his obser- 

 vation ; and I hope the result will be that, with our numerous ob- 

 servers, we shall be enabled to prove that a " boring sponge" is 

 about as true a fact as the "barnacle goose." 



I will now quote from the work on the microscope to which I 

 have alluded, as the passage, fortunately for our purpose, has con- 

 densed and brought together all the popular ideas, and what I 

 assert to be, errors on the subject : — 



" Cliona. — Not the least wonderful circumstance connected 

 with the history of sponges is the power possessed by certain 

 species of boring into substances the hardness of which might 

 be considered as a sufficient protection against such apparently 

 contemptible foes. Shells (both living and dead), coral, and even 

 solid rocks, are attacked by these humble destroyers, gradually 

 broken up, and no doubt finally reduced to such a state as to 

 render substances which would otherwise remain hard and useless 

 in the economy of nature available for the supply of the necessities 

 of other living creatures. 



" These boring sponges constitute the genus Cliona of Dr. Grant. 

 They are branched in their forms, or consist of lobes united by 

 delicate stems ; they all bury themselves in shells or other cal- 

 careous objects, preserving their communication with the water by 

 means of perforations in the outer wall of the shell. The mechanism 

 by which a creature of so low a type of organization contrives to 

 produce such remarkable effects is still doubtful, from the great 

 difficulties which lie in the way of coming to any satisfactory con- 

 clusion upon the habits of an animal that works so completely 

 in the dark as Cliona Celata ; it probably will long remain so. 



"Mr. Hancock, to whom we are indebted for a valuable memoir 

 upon the boring sponge, published in the ' Annals and Magazine 



