xix BRITISH MARINE GENERA 529 



40. 



41. 



42. 



43. 



44. 



45. 

 46. 



f Zooecia arranged in regular series . . . .41 



( Zooecia irregularly ] heaped together (cf. No. 30) . CeUepora 



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 



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

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

 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. Schizotlieca 

 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) 



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

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

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

 V. not completely tubular . . . . .49 



j Orifice not tubular. A median pore 

 \ Orifice tubular 



( Zooecia narrow or small 

 { Zooecia ovoid . 



( Orifice markedly tubular. Median pore conspicuous 



48 



49. 



Microporella (Fig. 241, A) 

 . 46 



. 47 



. 48 



Porina tubulosa 



arranged, with no median 

 Celleporella 



surface : ovicells set far back. 



47. < Colony very small. Zooecia irregular 

 ( pore 



' Zooecia very convex, with a granular 



Orifice wider than long . . . Mucronella microstoma 



Young zooecia with stellate pores. A minute avicularium, or merely 



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



Anarthropora monodon 



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

 ) Area not present 



50. 



f Front wall wholly calcareous . 



\ Front wall wholly or partly membranous 



55 



51 

 54 



1 For Celleporella (colony minute : orifice tubular), see 41 et seq. 

 9 Ehynchozoon (see No. 61), in which the primary orifice becomes much obscured 

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



VOL. II - M 



