AIE. A. W. WATERS OK MEMBRANIPOlilD^. 661 



No. 4. M. MEMBRANACEA group. — No avicularia, no ovicells, 

 DO pore-chambers. Operculum witli thickened border. Inter- 

 tentacular organs known in M. memhranacea. 



No. 5. M. COBBULA group. — Zooecia with spines over the 

 front ; ovicells mostly with a rib ; avicularia frequently vicarious ; 

 usually poie-cbambers. 



No. 6. M. ECHINUS group. — Ovicells unknown; avicularia 

 pediculate or articulate. 



No. 7. M. LiNEATA group. — Ovicells with rib ; pore-chambers 

 usually one distal, four lateral ones ; spines round the border. 



No. 8. M. BATELLAKiA group. — Ovicells when present cu ul- 

 late; mostly without avicularia. The front lamina directed 

 inwards below ihe proximal end of the oral aperture. The 

 zooecia joined by more or less tubular connections. 



No. 9. M. Plemingii group (AmpJiiblestrum, auct.) (Ram- 

 pTionofus, auct.). — Ovicells with more or less arched area on the 

 front ; usually lamina over considerable part of the front. Pore- 

 chambers. 



No. 10. M. xENTJiEOSTEis group. — Vicarious avicularia (dis- 

 similis) . 



No. 11. M. CRASSiMAEGiNATA group. — Ovicoll umbouate, 

 with partial rib ; avicularia vicarious. 



No. 12. M. CORONATA group. — Small avicularium above the 

 zocecium ; ovicells small, globular or cucullate. 



No. 13. M. HiAKs group. — "With denticular plate in the 

 aperture. Rosette-plates fairly numerous. Zoarium may be 

 unilaminate or bilaminate in the same species. Perhaps this 

 group should be removed from Memhranipora. 



No. 14. Ontchocella akgulosa group. — Avicularia vicarious ; 

 ovicell, which is known in very few cases, is small, shallow. 

 This group was abundant in the Tertiary and Cretaceous 

 formations. 



No. 15. Membbaniporella. — There are pore-chambers. The 

 thick operculum is attached to the front membranous wall, and 

 is in no way connected with the overarching ribs. In Crihrilina 

 the ribs form the front wall and the " complete " operculum fits 

 into the corresponding calcareous aperture. Membranijporella 

 is closely allied to Group 5, and this again dovetails into Group 7. 

 The Memhraniporell(S will be more fully studied when the Cribri- 

 linidse are taken in baud. 



LINN. JOURN. — ZOOLOGY, VOL. XXVI. 47 



