PLUMATELLA CORALLOIDES. 103 



mode of growth : and from the latter it is at once known by its cylindrical branches and 

 narrow statoblasts. In its general habit it bears a very close resemblance to Fredericella, 

 indeed from a luxuriant specimen of the latter polyzoon it is frequently impossible to 

 distinguish it without an inspection of the polypides or statoblasts. 



I have found this species throughout the entire summer and autumn. 



6. Plumatella coralloides, Allman. PI. VII, figs. 1 — 4. 



Specific character. — Coenoecium attached only at its origin, and forming dense, erect 

 tufts of dichotomously branched tubes, destitute of furrow and keel. Tentacula about sixty. 

 Statoblasts broad. 



Synonym. — 1850. Plumatella coralloides. Allman, Brit. Assoc. Report, 1850. 



Iconography. — No published figure. 



Habitat. — Attached to submerged bodies in still water. Avoiding the light. 



Locality. — The " London Docks" on the River Thames. Mr. Bowerbank and G. J. A. 



This species rises to the height of from half an inch to an inch, in the form of dense 

 tufts, consisting of tubes which repeatedly branch in a dichotomous manner as they extend 

 upwards from the base. The branches are approximated, and are formed of a series of 

 pellucid tubular cells, which are for the most part dilated upwards, and thus present a sort of 

 claviform figure, while the ultimate ramuli, varying in length, bring all the orifices to the 

 same level, and give to each tuft somewhat the appearance of certain varieties of that form of 

 inflorescence known to botanists by the name of ci/me. Almost every cell is separated from 

 its neighbour by a very complete transverse septum. This septum is of a dark reddish- 

 brown colour ; and being visible through the pellucid walls of the cell, gives to the tubes 

 the appearance of being divided at regular intervals into distinct joints. The cells are light 

 yellowish-brown, of a membrano-corneous texture, and nearly free from earthy deposit. 



P. coralloides presents in habit a very close resemblance to Alcyonella fungosa ; indeed, 

 it must be viewed as possessing an intimate relation with the latter Polyzoon ; the already 

 approximated branches need but advance one step further in their approximation, and by 

 adhering to one another, give rise to a genuine Alcyonella, scarcely distinguishable from 

 A. funyosa. 



The present species occurred rather abundantly in the London Docks, on the River 

 Thames ; where, in company with Mr. Bowerbank, I met with it in July, 1849, attached to 

 floating logs of wood, together witli P. repem and Cordylophora lacusfris, and generall}' 

 immersed in masses of Spongilla fluviatilis. 



