BRITISH ZOOPHYTES. 255 



distinguislied throug-h the cells. As it advances in 

 age tlie opening below the mouth looks as if it was on 

 a raised knob, and the flat appearance of the cell is 

 gone. The other extreme form is one in which the 

 side horns and the heavy knob are so prominent as to 

 be the leading features of the species. In modified 

 instances the front protuberance is lower and the horns 

 less distinct.'^ 



4. M. viOLACEA, Johnston. 



Lepralia violacea (G. J., Bush, 3£anzoni, D. L.), L. 

 plagiopora {Busli), L. diversipora [Beuss], Porina 

 violacea (Smitt), P. plagiopora {Smitt). 



Hab. : Isle of Man (Forhes), Cornish Coast {G. W. P.), 

 Hastings {Miss Jelly), Brixham, Torbay, Guernsey 

 (T.H.). 



This species forms irregular crusts of a violet or 

 cream colour on shells, stones, &c. The cells are ovate, 

 with a rough granular surface, depressed in the middle, 

 where there is a large circular median pore. There is 

 also an avicularium. The old cells lose their beauty 

 and become " almost confluent of a dead whitish colour, 

 flatfish and sometimes thickly perforated.'^ In a 

 specimen now before me the perforations are extremely 

 large. 



Genus II. Dipokula, HincJcs. {SU, double.) 



Zooecia with the orifice arched and expanded above, 

 contracted below, and slightly constricted by two 

 lateral projections (horseshoe-shaped), lower margin 

 straight ; a semilunate pore on the front wall. Avicu- 

 laria. — T. H. 



1. D. VERRUCOSA, Peach. 



Eschara verrucosa {G. W. P.), E. lunaris {Waters). 



