304 Rey. T. Hincks’s Catalogue of Zoophytes 
varieties, I can find no distinction between them in the minute 
characters. 
2. C. Hassallii, Johnston. 
Occasional, on shells and stone; on Anomia from Plymouth ; 
on stone from 30 fathoms, Cornwall (very fine), &c. 
3. C. edax, Busk, ‘ Polyzoa of the Crag,’ p. 59, pl. 9. fig. 6, 
pl. 22. fig. 3. 
On a Turritella (?) from Plymouth. 
Of this very curious form I have only obtained the single 
specimen referred to by Mr. Busk in his ‘Monograph; and I 
am not aware that any other recent example has occurred. It 
seems to be not uncommon in the Coralline Crag. 
The Devonshire specimen, which has been moulded on a small 
univalve shell, probably a Turritella, is in very fresh condition, 
and shows the minute characters well. Like its fossil kindred, 
the Cellepore has completely removed the substance of the shell 
on which it originally took up its abode. Nothing now remains 
but the form, which is perpetuated by the stony crust of the 
Polyzoon. 
A strictly analogous case occurs amongst the Actinozoa. A 
Zoanthus has been described by Diiben and Koren, under the 
name of Mamillifera incrustata, which is commonly parasitic on 
shells that are tenanted by a species of Pagurus. In all cases, 
however, the shell is destroyed after a while by some process of 
erosion or absorption, the diffused basal crust of the Zoophyte 
forming a perfect cast of it, and affording shelter to the crab. 
This form occurs in Shetland and the north of England, as well 
as in Norway, and is regarded by Mr. Gosse as a variety of Z. 
Couchii. Taking into account, however, the differences in the 
number and colour of the tentacles, which the northern natu- 
ralists have pointed out, and in the characters of the base, as 
well as the remarkable peculiarity just referred to, I am inclined 
to regard the M. incrustata as a distinct species. 
4. C. avicularis, Hincks. Pl. XII. figs. 6, 6a, 
‘Microscopical Journal,’ vol. viii. p. 278. 
Common, encrusting the stems and branches of Zoophytes 
from deep water, with large and nodulous rolls. The Gorgonia 
is frequently laden with masses of it. 
This is one of the best-marked of the crustaceous Cellepores 
—a most perplexing tribe to deal with. After the repeated ex- 
amination of a multitude of specimens, I find myself quite un- 
able to speak with confidence as to the forms which are entitled 
to specific rank; indeed the bewilderment increases with the 
number of specimens examined. 
