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.
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