Mr. J. Morris on the Excavating Sponges. 239 



XXV. — Observations on Mr. Mdxicock^^ paper on the Excavating 

 Sponges. By John Morris, F.G.S. 



In the interesting communication " On the Excavating powers 

 of certain Sponges/^ &c. which appeared in the May Number of 

 the ' Annals/ Mr. Hancock appears to have overlooked a paper 

 published some time since by an Italian naturalist in which the 

 same facts are fully and clearly described. Had this paper been 

 more generally known, probably "the prevailing belief that Cliona 

 does not excavate the chambers in which it is found, but that 

 they are formed by worms or by decay," &c., might have been 

 somewhat shaken, and " the matter which has remained up to the 

 present time in obscurity " more clearly defined. It may there- 

 fore be interesting to some of the readers of this Journal to give 

 a short abstract of what was previously known on this subject, 

 not merely for advocating the priority of discovery, but as 

 strengthening the opinion as to the excavating power of these 

 bodies, so admirably illustrated by Mr. Hancock*. 



Ten years have elapsed since Dr. Nardo communicated, in the 

 name of his brother, to the Scientific Congress held at Pisa in 



1839, a paper " On a new genus of Siliceous Sponges, named 

 Vioa, living in excavations formed by itself in stones and in the 

 shells of marine mollusca, boring them in every direction.'' This 

 sponge consists of numerous small very fine acicular siliceous 

 bodies arranged irregularly in a fleshy but not mucous substance, 

 of a yellowish, orange or purple colour, permanent or fugacious 

 according to the species. At certain periods of their growth, 

 these sponges emit small germs visible to the naked eye, which 

 transported by currents attach themselves to stones or marine 

 shells, and commence to form passages in their substance, rid- 

 dling them in every direction, so as even sometimes to destroy the 

 stone or shell, leaving the sponge isolated and free. Dr. Nardo 

 observed the following species all obtained from the Adriatic, and 

 named by him Vioa typusj coccinea, Clio, Pasithea-f. 



At a subsequent meeting of the same Congress held at Milan 

 in 1844, M. Michelin, whose attention had been previously di- 

 rected to the point, read a short notice on the same subject, in 

 which he alluded to the traces of an organized zoophytic body 



* It is but justice to Mr. Hancock to state, that his description of the 

 means by which these sponges perforate calcareous substances is both novel 

 and interesting. 



f Atti della prima riunione degli Scienziati Italiani tenuta in Pisa. 1839, 

 p. 161 ; Pisa, 1840. A fuller notice of this paper is in (he ' Annali delle 

 Scien. del Reg. Lomb.-Venet,' vol. ix. p. 221 ; see also Revue Zoologique, 



1840, p. 27. In the same journal (p. 343) is M. Duvernoy's description of 

 Spongia terebrans^ inhabiting the valves of Oslrea hippopus, Lam. 



