242 ZOOPHYITES. 



In those places to whicli I have had access, the product here named 

 Cellularia aviculari'^, has always grown as a parasite on the Flusira trun- 

 cata, a foliaceous zoophyte. I do not recollect observing it elsewhere, which 

 shews either that the same conditions are favourable to both, or favourable 

 to the particular kind of developement then attained by the avicularis. 



In studying zoophytes, it is necessary to reflect, that developement 

 is much governed by situation, which has the greatest influence both on 

 dimensions and perfection. 



On the leaf of the Flustra truucata, this product assumes somewhat 

 the form of a pine or larch, rising above an inch in height by a short stem, 

 around which the boughs are disposed, rather in a spiral arrangement. 

 The second originates a little above the first or lowest, a third still higher 

 than the second. All shorten in proportion as higher, with a slight incur- 

 vature of both the interior and exterior parts towards the stem, so that 

 the whole form of a perfect specimen is conical. — Plate XLVIII. fig. 1. 

 XLIX. enlarged. But this is not alike definite in smaller specimens. 

 All the subordiate parts terminate in a cell, whicli, in perfection, seems 

 to be guarded by three marginal spines. Some have two, many only one. 

 Possibly three form the complement. The root runs superficially over the 

 Flustra, secured by four radicles. 



As in the Fastigiata, the dichotomous configuration and relative posi- 

 tion of the parts must be sought for more conspicuously by the aid of the 

 microscope. — Plate XLVIII. figs. 2, 3. 



A lively ascidian hydra with 14, 15, and, I believe, sometimes 16 ten- 

 tacula, inhabits the cells. — Figs. 4, 5. Numerous brown ovoidal corpus- 

 cula remain in those which are vacant ; and a spherule rests on the ori- 

 fice of many, also vacant, where there is no room for more. This is brownish, 

 or paler and thinner as if empty. 



A number of Avicularia bordered the branches of the specimen. — 

 Plate XLVIII. fig. 1, such as described in the following paragraph. 

 They appeared smaller than ordinary, and were at first motionless, though 

 displaying sufiicient activity two days after. — Fig. 6. 



Dingy yellow, brown, red, and grey are agreeably contrasted in the 

 various parts of the product. 



