60 THE CRAG POLYZOA. 



found, it appears to be reduced to extreme tenuity, and its outer surface to have been 

 eaten away as it were by the parasitic incrustation. I am unable to determine the 

 species of shell which appears to have constituted the most frequent nidus of this 

 Cellepore, but it appears to have been of small size, with a circular mouth. It is to 

 be remarked, also, that other shells, either entire or in fragments, together with minute 

 pebbles, are occasionally found imbedded in the parasitic mass. A curious instance of an 

 apparently living shell having been thus partially entombed is presented in a specimen afford- 

 ing lodgment to a minute Anomia, with a smooth subovate upper valve, and a very perfect 

 under valve. The edge of the larger valve just appearing on the surface of the Cellepore, a 

 small portion of the latter was cleared away, when the perfect Anomia, with the nacreous 

 lustre quite perfect, and the valves in their undisturbed natural apposition fell out, leaving 

 a cavity, one side of which, corresponding apparently to the lower valve, was smooth and 

 accurately moulded to the surface of the imbedded shell, whilst the opposite was rough 

 and porous, like the general surface of the polyzoary. From this it may probably be 

 concluded that the Anomia was thus entombed alive, and that sufficient space was left 

 for the movement of the upper valve. Not being certain that his is the var. y of Cell, 

 pumicosa, noted by Mr. S. Wood, under the term C. pustulosa, I have not introduced that 

 synonym, and am the more inclined to omit it, since C. edax is altogether distinct from 

 the Cettepora pustulosa of Goldfuss (' Petr.,' p. 102, pi. xxxvi, fig. If-). Cellrpora 

 parasitica of Michelin ('Icon. Zoophyt.,'p. 326, t. Ixxviii, fig. 3), is in habit very similar to 

 C. edax, but in that species the imbedded shell appears to be unaffected by the parasitic 

 growth, and to retain its natural markings. The species of shell inhabited by it is also 

 different, and the description given of the cells, insufficient as it and the figure may be, 

 would lead to the conviction that the two cannot be identical, though undoubtedly 

 closely allied. 



Whilst these sheets are passing through the press, I have received, through the kind- 

 ness of the Rev. T. Ilincks, a specimen of a Cellepore found on the coast of Devonshire, 

 in all respects identical with C. ednx of the Crag. Like that species, the recent form 

 presents the shape of a small tnrrited shell, probably a Turritella ; but what is especially 

 worthy of remark, the shell itself, so far as can be seen, is as completely removed as it is 

 in the fossil Cellepore. That the destruction of the shell, cannot be regarded as 

 accidental, but as due to a specific action in the parasitic growth, is rendered the more 

 probable when it is found to take place in the recent as well as in the fossil state. 



6. C. TUBIGERA (n. sp.) PI. IX, figs. 8, 10. 



Polyzoario adnato subhemispherico, sen conico. Cellulis distantibus, sparse punctatis ; 

 processu unico tubuloso ascendente, avicularium summitate gerente plerumque uno latere 

 tantum munitis. 



