19. 



20. 



21. 



r 



22 



xix BRITISH MARINE GENERA 527 



Characters as in No. 6 . Kucratea chelata, Huxleya /myitis 



Zooecia biserial. Aperture large, the semicircular orifice at its upper 



end, where there is commonly a short spine Gellularia peadlii 



Zooecia in one or two series. Branches originating from the backs 



of the zooecia, and facing in the opposite direction to the parent 



branch. A.perture small . . . Scnqparia clavata 



One or more conspicuously long marginal spines. Avicularia present 

 or absent ...... Bicellaria 



Zooecia uniserial (see No. 5) . . . Brettia 



Zooecia biserial, in short internodes. An inconspicuous avicularium 



below the aperture. Fornix present . Mtnipea jeffreysii 



Colony consisting of a network of narrow branches, the zooecia 

 opening only on one of their surfaces . . Retepora 



Colony large, brittle, composed of contorted plates, uniting irregularly, 

 usually composed of two layers of zooecia. Orifice large, indented 

 laterally ..... Lepralia foliacea 



Branches delicate, cylindrical . . . . .22 



Branches or lobes coarser, not necessarily cylindrical . .24 



Branches composed of four rows of zooecia . . .23 



Zooecia in more than four regular, longitudinal rows. Peristome 



raised, and, with the ovicell, forming a swelling on the surface of 



the branch . . Eschar oicles quincuncialis 



f Orifice circular. A row of pores round the margin of the zooecium. 



A median pore resembling a small orifice below the true orifice. 



23 J Small lateral avicularia . . . Porina borealis 



Orifice surrounded by a peristome, produced into a mucro beneath 



the orifice. No pores . . . Palmicellaria elegans 



( Zooecia arranged in regular series . . . .25 



J Zooecia irregularly heaped, their long axes often perpendicular to 

 J the surface of the colony. Mucro largely developed, concealing 

 \ the form of the orifice, and bearing an avicularium Cellepora 



) Orifice with a sinus ; or peristome interrupted or extended below 

 into a sinus-like outgrowth, which usually includes a small 

 avicularium . . -6 



Neither median sinus nor interrupted or extended peristome . 28 



, / Orifice with a sinus . ; . Schizoporella (Fig. 239, B) 



' \ Peristome interrupted or extended below . . - ~ 



Branches of various forms. Surface of the older parts very even. 

 Secondary orifice rather long, usually wider above, enclosing a 

 small avicularium below, and appearing as a hole in the even 

 surface of the branch . . Porella (Fig. 255, B, C) 



A prominent tooth projects into the orifice from its lower side. 

 Zooecia with thin walls . Bmittia landsborovii (Fig. 239, C) 



No tooth in the orifice, at the side of which is a small avicularium. 

 Old zooecia with thick walls. Colony composed of a short stem 

 and flattened branches . . . Escharoides rosacea 



26 



27 J 



