218 MICROPORELLID.E. 



tributed over the zoarium. In this variety too the surface 

 is either smooth or minutely granulated, like shagreen. 



L. plagiopora, Busk, from the Crag, should probably 

 be ranked as a variety of the present species. It differs 

 from it in the size and oblique direction of the avicula- 

 rium points which taken by themselves are of very small 

 moment. 



Smitt has suggested that if from any cause the avicu- 

 larium were more fully developed than usual, as not 

 unfrequently happens in other species, it might probably 

 take an oblique direction to obtain sufficient space. 



In a beautiful specimen from the Crag (Plate XXX. 

 fig. 4) each cell is bounded by an incised line, within 

 which is a row of numerous small punctures, which are 

 occasionally channelled. 



M. violacea is commonly of a dark purplish colour; 

 but cream-coloured specimens not unfrequently occur. 

 Heller remarks that the light-coloured form is pretty 

 common in the Adriatic, but that he had only observed 

 the dark violet variety once. 



HABITAT. On shells, stones, Nullipores, &c., generally 

 in moderate depths. 



LOCALITIES. Isle of Man (E. Forbes) : Cornwall (Peach) : 

 Brixham, from the trawlers ; Torbay ; off the Deadman ; 

 Guernsey (T. H.) : Birterbuy Bay (G. S. Brady). 



Var. a. Guernsey, abundant (T. H.) : Hastings (Miss 

 Jelly). 



GEOGRAPHICAL DISTRIBUTION. Roscoff, extreme low- 

 water mark (Joliet) : Algiers (J. Y. J.) : Adriatic, the 

 light-coloured variety pretty common, the dark violet once 

 on Nullipore (Heller) : Gibraltar Bay (Landsborough) : 

 M a/at lai i , on Murex and Byssoarca pacifica ; Adelaide, a 

 much thickened variety (T. H.) : west off Tortugas, in 

 35 fathoms (Pourtales) : Charente-Inferieurc (Fischer). 



