BRITISH ZOOPHYTES. 277 



(b) With a raised secondary orifice. 

 Genus III. Porella, Gray. 



Zooecia with the primary orifice semicircular; 

 secondary (or adult) orifice elongate, inversely sub- 

 triangular or borseshoe-shapedj inclosing an avicu- 

 larium, usually with a rounded mandible. Zoarium 

 incrusting, or erect ; foliaceous, with a single layer of 

 cells, or ramose. — T. H. 



This genus comprises some species which are in- 

 crusting, and others which are erect and branching : 

 the first and second species are of the former type. 



1. P. CONCINNA, Buslc. 



Lepralia concinna {Bush, McA., HincJcs), L. aperta 

 {BoecJc), L. Belli {Dawson). 



Hab. : Widely distributed. 



The colonies are cii-cular, and of a red colour. The 

 zooecia vary considerably, but are all distinguishable 

 by the orifice, which is arched, contracting towards a 

 straight lower margin. Round the orifice the cell wall 

 often forms a distinct thickened shoulder, and inside 

 is a broad denticle. The surface of the zocecia is usually 

 plain, with punctures round the margin; but in some 

 varieties the punctures extend over the entire area. 



2. P. MINUTA, Norman. 

 Lepralia minuta {A. M. N.) . 



Hab.: Shetland, Guernsey {A. M.N.), Wick {G.W. P.), 

 Hastings {Miss Jelly). 



This species is, as its specific name implies, very 

 small, and " forms small roundish patches.''^ It very 

 much resembles the preceding species, being distin- 

 guished by its smaller size, and the regular linear 

 arrangement of the cells. 



