530 P0LYZ0A 



51. 



Avicularian or vibracular zooecia replacing an ordinary zooecium, or 

 at least situated between the zooecia . . 5 2 



Avicularia and vibracula absent, or if present not replacing a 

 zooecium . . . . . . f>3 



53. 



(Vibracula present. Colonies small. A pair of longitudinal slits 

 within the area .... Setosella vulnerata 

 oz. < Very large avicularia present. Ovicell closed by a movable lid. 

 Orifice subcircular, with a minute lateral tooth on each side. 

 y Thalamoporella l (Steganoporella) smittii 



f Orifice semicircular, quite at the upper end of the zooeiium ; usually 

 with a knob on each side . Micropora coriacea 2 (Fig. 256, C) 

 A transverse chitinous plate lies immediately below the operculum. 

 A vibraculoid spine may occur . . Megapora ringens 



r Area entirely membranous, usually bordered by sjunes. 



Membranipora (including Electra 3 ) (Fig. 256, A) 



54. -J Membranous portion reduced to a small portion, which may be 

 variously lobed, enclosing the orifice. 



Membranipora (other species) (Fig. 256, B) 



f Peristome present. No mucro . . . .56 



55. -J Peristome absent ; or if present, with a mucro . . .57 



I (See also Mucronella pavonella, No. 28). 



/"Peristome collar-like, much raised below and at the sides of the 

 orifice, deficient above. No avicularia . . Phylactella 



I Orifice large, longer than broad. Peristome not deficient above the 

 V orifice ...... Lepralia 



(Wall of zooecium thin, shiny, and without pores . .58 



Not agreeing with the characters given under No. 58 . .59 



' A minute avicularium above the orifice, or where an ovicell is present, 



situated at the summit of that structure. Zooecia not quite 



contiguous. Mucro sometimes present . Ghorizopora brongniartii 



No avicularia. Ovicells on rudimentary zooecia, lying in a plane 



superficial to that of the rest of the colony. Zooecia long. 



I Schizoporella hyalina 



{A more or less distinct mucro or prominence beneath the orifice. 60 

 Mucro rarely present. Orifice nearly always longer than broad, or 

 nearly circular, usually large, and slightly indented laterally. 

 Lepralia 



(A tooth projects into the orifice from its lower side . .61 



No tooth . . . . . . . 62 



56. 



58. 



60. 



1 Hincks, J. Linn. Soc. xxi. 1889, p. 123. 



a Micropora complanata, Norman, should be placed in the genus Lepralia. See 

 Hincks, Ann. Nat. Hist. 5 ser. xix. 1887, p. 304. 



3 See Norman, Ann. Nat. Hist. ser. 6, xiii. 1894, p. 113. 



