236 ZOOPHYTES. 



is very pale, almost colourless : but the opacity of the cells precludes a 

 satisfactory view of their conteuts. 



Some specimens appear speckled red. 



The vegetative faculty of specimens, though abortive of animals, 

 seems to be denoted by numerous slender prolongations, scarcely grosser 



than hairs. 



Many minute beings seek shelter among the multitude of cells, from 

 whence they either issue forth occasionally, or are dislodged by the im- 

 purity of the water. 



Besides its foundation on the Flustra foliacea, this Cellularia estab- 

 lishes itself on the external surface of various shells, or it finds a safe and 

 convenient nidus within some, such as those of the mussel and oyster, when 



empty. 



The specimen represented, being perfect, was selected from among 



many. 



Plate XLV. Fig. 1. Cellularia reptans — Creeping Coralline. 



2. The same, enlarged. 



3. Aspect and arrangement of the cells, enlarged. 



4. Portion of the hydra which is exposed, enlarged. 



§ 3. Cellularia fastigiata (Sertulaeia fastigiata, Linnatis). — 

 Plate XLVI. — It is often very embarrassing to determine the identity of 

 species, or whether a certain subject before us may not be a mere variety. 



Spite of all precautions, I feel very sensibly that I have been some- 

 times misled by appearances ; whence, if our arrangements shall be guided 

 by the structure of the inorganic parts, when life has fled, I believe that 

 they will afford greater facilities than the animated subject. 



We can readily account for embarrassments resulting from the mi- 

 nuteness and frequent indistinctness of the organs of zoophytes : from the 

 alteration of their relative position by age and increment, that elusory 

 characters are necessarily assigned to many, from different observers hav- 

 ing assumed younger or older specimens ; the barren or prolific : that vari- 

 ous portions of the same specimen, where common features peculiar to 



