Mr. J. Morris on the Excavating Sponges. 241 



the genus Vioa, as well as to some inaccuracies of those authors 

 who have written after him. He mentions that Dr. Johnston has 

 not even suspected the Halichondria ccdata (which is a Vioa) to 

 be a perforating sponge ; and also opposes the opinion of 

 M. Dujardin, who thought that the perforations in shells and 

 stones (which he, Dr. Nardo, had proved to be the work of a 

 sponge) were at first occupied by small species of Annelides, and 

 that the sponge subsequently inhabited their cavities. Dr. Nardo 

 does not think that the name Cliona ought to be preferred to that 

 of Vioa proposed by him, because Dr. Grant, in establishing his 

 genus, did not consider it to be a sponge, but a polype having 

 eight tentacula ; and he consequently proposes that the Spongia 

 terebrans, Duvernoy, which M. Dujardin regards as a Cliona, 

 should be named Vioa Dujardinii, if however it is distinct from 

 the species already described*. 



Since the publication of this report for 1844, M. Michelin has 

 observed a valve of Meleagrina margaritifera, Lam., and speci- 

 mens of the genera Conus and Fusus perforated by species of 

 Vioa, as well as a valve of the fossil, Trigonia Dadalea, Park. 

 M. Michelin has also noticed traces of the same genus on frag- 

 ments of fossil shells from the chalk of Orglandes and the supra- 

 cretaceous beds of Grignon (Revue Zoologique, 1846). 



The following species of Vioa appear to be identical with two 

 of those described as Cliona by Mr. Hancock. 



Vioa Nardina, Michelin, Rev. Zool. 1846, pi. 1. fig. 1. 



V. dendritica, dichotoma, ramosissima, utriculis et tubulis compo- 

 sita ; utriculis vel rotundis vel ellipticis in seriebus eleganter dis- 

 pose tis, inter se junctis per tubulos exiguos interne rugosos ; tu- 

 bulis terminalibus, acutissimis, ssepe furcatis. 



Inhabits the upper valve of the P lacuna placenta, Lam. 



This species is identical with Cliona Fryeri, Hancock, Ann. 

 Nat. Hist. 1849, p. 338. pi. 14. f. 2 ; and that author described 

 it as imbedded in the same shell. 



Vioa Michelini, Nardo, Rev. Zool. 1846, pi. 1. fig. 2. 



V. dendritica, dichotoma, divaricata, utriculis et tubulis composita ; 

 utriculis numerosis, vesiculosis, subpolygonis, interne rugosis, ve- 

 tulis maximis, junioribus parvulis, elongatis, deinde subrotundis, 

 per minutissimos tubulos junctis et anastomosantibus. 



Inhabits the upper valve of Placuna sella, Lam. 



This species is the same as the Cliona spinosa, Hancock, Ann. 



* Atti della sesta Riunione degli Scien. Ital. tenuta in Milano, 1844, 

 pp. 372, 428, and Revue Zoologique, 1846 ; see also Annali delle Scien. del 

 Keg. Loin!).- Yen. 1845, p. 11. 



