224 MK. J. W. GEEGOKY ON THE 



Family 11. MembraniporidjE. Athyriata with the front wall mainly membranous and occupied 

 by an opesial aperture ; this does not correspond to the operculum. The opesium is sur- 

 rounded by a raised margin. External ocecia. 

 Subfamily 1. MemhraniporincB. Membraniporida with open opesia and without, or with but a 



small, extra-opesial front wall 

 Subfamily 2. Electrinirue. Membraniporidse with the normal zoceeia tubular and with a 



terminal opesium. 

 Subfamily 3. LunuUtirue. Membraniporidse with patelliform zoaria, and with vibracularia 

 systematically arranged. 

 Family 12. Cribrilinid.*. Athyriata with a fiont wall formed by the overarching and branching 

 of one or more spines. External ooecia. 

 Subfamily 1. Cribrilininoe. Cribrilinidae with the front wall formed by the overarching and 



fusion of numerous circumareal spines ; the interspaces remain as grooves or pores. 

 Subfamily 2. Hiantoporina. Cribrilinidae with the front wall formed of one large spine arising 



from the margin. 

 Subfamily 3. Steginoporirue . CribrilinidEe with the front wall formed by the overarching of 

 spines arising from the peristome. 

 Family 13. MicROPORiDa;. Athyriata with a calcified front wall. Zooecia surrounded by raised 

 margins. No internal diapliragms. External ooecia. 

 Subfamily 1. Mieroporinte . Zooecia all normal or onychocellaria (large vicarious avicularia) 



irregularly distributed. 

 Subfamily 2. Selenarina. Microporidse with patelliform zoaria and vibracularia systematic- 

 ally arranged. 

 Family 14. Steganoporellidve. Athyriata without external ooecia and with the zooecia divided 



into two chambers by a calcareous diaphragm. 

 Family 15. Cellariid.e. Athyriata with internal ooecia which open by a pore above the aperture. 

 The zooecia are surrounded by raised margins ; the aperture is situated within the 

 depressed front wall, 



IV. Suborder Schizothyriata. 



Cheilostomata which are schizostomatous or trypiate {i. e. provided with a trypa ; see p. 220) 

 or both. 

 FamUv 16. SchizoporblliDjE. Schizothyriata not provided with a trypa. 



Subfamily 1. SchizoporellineB. Schizoporellidse with simple primary aperture and external 



ooecia. 

 Subfamily 2. Schisoreteporinea.' Schizoporellidse with the zooecia obliquely placed on a, 



unilaminar, reticulate or ramose, erect zoarium. 

 Subfamily 3. ScMsmoporincB.^ Schizoporellida; with urceolate zooecia growing in dense 



masses ; aperture terminal or subterminal. 

 Subfamily 4. Biporineie. Schizoporellidie with a patelliform unilaminate zoarium, with 

 vibracularia systematically arranged. 



' Schizoi-etepora, n. gen,, for which at present the subfamily di^nosis also serves as the diagnosis, Ls the type 

 genua ; it includes the schizostomatous Eeteporas, of which .S. (i?.) lesselhta (Hincks) [No. 2, p. 3.58, pi. six. 

 figs. 9-12], is a convenient type. 



- Schismopora, MacgiUivray [No. 4, p. 29], is the type genus, and S. costata the tj'pe species : it does not 



