THE ANNALS 
AND 
MAGAZINE OF NATURAL HISTORY. 
[SECOND SERIES.] 
No. 17. MAY 1849. 
XXXVI.—On the Excavating Powers of certain Sponges belonging 
to the genus Cliona ; with descriptions of several new Species, 
and an allied generic form. By Aupany Hancock, Esq. 
[ With four Plates.} 
Wuize engaged in mvestigating the method by whieh the Mol- 
lusca bury themselves in stone, wood, and other hard substances; 
-I was naturally led to examine the pe a et inhabited by Cliona ; 
and having arrived at the conclusion that they are not the de- 
serted abode of worms, or cavities accidentally formed by erosion 
or otherwise as has been stated, but that they are worked out 
by this curious production itself, [ asserted such to be the case 
in a paper communicated by me to the last Meeting of the Bri- 
tish Association. Since then I have gone more fully into this 
subject, and as the prevailing opinion appears to be adverse to 
that expressed by myself, 1 purpose now giving a detailed account 
of the facts, which I trust will be deemed sufficient to justify my 
former statement. 
My investigations have led to the discovery that Cliona celata 
does not stand alone as an aberrant type, but that it is, in fact, 
a member of a large group of beings, hitherto almost entirely 
overlooked, which play apparently a most important part in the 
ceconomy of nature. I have determined upwards of fifty species 
of this curious sponge, all mhabiting more or less diversified 
chambers in calcareous substances, and in other respects well-cha- 
racterized. Of these species twelve belong to the British seas ; 
the rest are from various parts of the world. I have also ascer- 
tained that Cliona existed during several geological periods, and 
with the assistance of Mr. W. K. Loftus have determined that it 
occurs in the crag, in the London clay, in the Paris basin, in the 
chalk, in the greensand, and in the oolite ; and Mr. Alder has de- 
tected it in specimens of Pecten Islandicus from a raised beach 
on the coast of Bute. In most instances the characters of the 
Ann. & Mag. N. Hist. Ser. 2. Vol. iu. 21 
