PORELLA COMPRESSA. 333 



extending for a short distance below the primary open- 

 ing ; and around this and the original mouth the cell-wall 

 is gradually elevated, forming the elongate and somewhat 

 horseshoe-shaped orifice of the adult cell. 



In some cases the zooecia towards the upper portion of 

 the branches are deeply immersed, and covered with a 

 considerable thickness of stony crust, the original mouth 

 and avicularium are sunk below the surface, and the actual 

 orifice is orbicular, contracted below into a narrow, 

 pointed sinus (Plate XLV. fig. 6). Such cells are flat, 

 strongly punctured round the edge and sometimes over 

 the whole of the front surface. Peach's Eschara sttllata 

 was probably founded on a specimen in this condition. 



HABITAT. On stones and rocks in deep water. 



LOCALITIES. Cornwall, common (Borlase, Couch) : De- 

 vonshire (Dr. Coldstrcam) : Embleton Bay, deep water 

 (R. Embleton) : Fifeshire coast, rare (Goodsir) : Shet- 

 land (Jameson) : ibid., 40-170 fathoms ; the Minch (A. 

 M. N.) : Nymph Bank, abundant (R. Ball) : Roundstone 

 Bay; off the Gobbins, co. Antrim (M'Calla) : Belfast 

 Bay (W. T.) : Youghal (Miss Ball). 



GEOGRAPHICAL DISTRIBUTION. West coast of Norway ; 

 Finmark, 30-50 fathoms (Sars) : Bahusia (Loven) : Spitz- 

 bergen (Swed. Exped.) : Greenland (Moller and Torell) : 

 Nova Zembla (West), 30-60 fathoms; Kara Sea (Stux- 

 l>erg and Theel) : Roscoff, common (Joliet). 



The synonymy of this species has been hopelessly con- 

 fused by our systematic writers ; and it bears a name in 

 their works to which it has no legitimate claim*. Mr. 



* An exception must be made in Dr. Johnston's favour, who clearly dis- 

 tinguished it from M.-Edwards's Etchara cervicornu (which is totally dis- 

 tinct and a Mediterranean form), and who had an excuse for giving it th<> 

 same specific name as the latter, inaftiuurh as he referred it to another 

 genud (Cellepora). 



