41 



43. 



x BRITISH MARINE GENERA 529 



J Zooecia arranged in regular series . . . .41 



' ( Zooecia irregularly l heaped together (cf. No. 30) . Cellepora 



Primary orifice conspicuous ; with a sinus, or with a peristome 

 extended or interrupted below, and sometimes simulating a 

 sinus . . . . . .42 



Neither sinus 2 nor interrupted peristome . . .44 



Surface of the old zooecia much thickened, so that the secondary 

 orifice does not project beyond the most prominent parts of the 

 zooecium. Secondary orifice concealing the primary orifice, wider 

 above, enclosing a small avicularium below Porella (Fig. 255, B, C) 



|' Primary orifice with a sinus, but no tooth . . .43 



I A prominent tootli projects into the orifice from its lower side. 

 I Peristome interrupted or with a sinus. Surface of the old zooecia 

 V. not much thickened .... Smittia 



Orifice with a sinus and long spines. Peristome interrupted. Ovicell 

 with a wedge-shaped or linear longitudinal fissure. Avicularia 

 generally present, the avicularian zooecium conspicuous. Schizotheca 



Orifice semicircular. Vibracula present, near the orifice. 



Mastigophora (Fig. 241, B) 



Orifice semicircular or subcircular. No vibracula ; avicularia with 

 vibraculoid mandibles may occur Schizoporella (Fig. 239, B) 



C Zooecium with a median pore ; or completely tubular above . 45 

 I Zooecium with no median pore. The orifice may be partially sur- 

 | rounded by a collar-like development of the peristome, but it is 

 V. not completely tubular . . . .49 



J Orifice not tubular. A median pore . Microporella (Fig. 241, A) 

 { Orifice tubular . .46 



f Zooecia narrow or small . .47 



b ' \ Zooecia ovoid . .48 



t Orifice markedly tubular. Median pore conspicuous Porina titbulosa 



47. 1 Colony very small. Zooecia irregularly arranged, with, no median 



( pore ' . . . CelleporelUi 



I Zooecia very convex, with a granular surface ; ovicells set far back. 

 Orifice wider than long . . . Mucronella microstoma 



Young /ooecia with stellate pores. A minute avicularium, or merely 

 a pore, on the upper and lower sides of the orifice in some zooecia. 

 Anarthropora monodon 



Front of zooecium with an elevated margin, enclosing an area . 50 



44. 



45. 



49> \ Area not present . 55 



(" Front wall wholly calcareous . .51 



\ Front wall wholly or partly membranous . . 54 



1 For Cellcporclla (colony minute : orifice tubular), see 41 ct srq. 



2 Hhyiu-luizwii (see No. 61), in which the primary orifice becomes much obscured 

 by the development of a large mucro, is placed in this section. 



VOL. II 2 M 



