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 celata (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 Dujardinit, 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, Trigonta Dedalea, 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, pl. 1. fig. 1. 
V. dendritica, dichotoma, ramosissima, utriculis et tubulis compo- 
sita; utriculis vel rotundis vel ellipticis in seriebus eleganter dis- 
positis, inter se junctis per tubulos exiguos interne rugosos; tu- 
bulis terminalibus, acutissimis, szepe furcatis. 
Inhabits the upper valve of the Placuna placenta, Lam. 
This species is identical with Cliona Fryeri, Hancock, Ann. 
Nat. Hist. 1849, p. 338. pl. 14. f. 2; and that author described 
it as imbedded in the same shell. 
Vioa Michelini, Nardo, Rev. Zool. 1846, pl. 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 
Reg. Lomb.-Ven. 1845, p. 11. 
