BRYOZOA. 113 



j. Acanthopores small, few or wanting.. XXXIX. Eridotrypa. 



j. Acanthopores large, abundant XLIII. Batostoma. 



j. Acanthopores absent XLVII. Callopora. 



11. Diaphragms few k. 



k. Mesopores small with subcircular openings. 



XXXVII. Batostomella. 

 k. Mesopores irregularly angular, often obscurely moniliform. 



XL VI. Trematopora. 

 8* Zoarium erect, flattened fronds or laminar expansions 12. 



12. Mesopores gathered into maculae, apertures en elevated stellate 



rays XLI. Conttellaria. 



12. Mesopores numerous, in interzocecial space, filled and obscured 



by calcareous tissue in older individuals.. XLII. Nichohonella. 

 8* Zoarium encrusting foreign bodies, apertures oval, mesopores abun- 

 dant XLI V. Stromatotrypa. 



8* Zoarium massive, hemispheric, subglobose or discoidal ; neither 

 mesopores nor acanthopores : zocecial walls often crinkled. 



XLV. Monotrypa. 



IV. CRYPTOSTOMATA. Zoaria compound often highly complex ; zocecia with a 



short tubular primitive portion, above which, in the " mature" part, is a tubular 



shaft or vestibule, often with hemisepta, and surrounded by vesicular or solid 



calcareous tissue ; external orifice round D. 



D. Zoarium a reticulated network or expansion pierced by holes or fenestrules and 



celluliferous on one side only % %. 



XX Branches and connecting bars or dissepiments distinct, the latter non- 

 poriferous 9*. 



9* Apertures on branches in two rows separated by a median keel ... 13. 



13. Keel moderate, plain, or tuberculated /. 



/. Funnel-shaped structure (fragments flat) L. Fenestella. 



I. Spirally wound axis LVII. Archimedes. 



13. Keel high, expanded at the summit m. 



m. Expanded portion of keel with large or scattered pores or 



pits LI I. Fenestrapora. 



m. Expanded portion of keel without pores or pits. 



LI. Semicoscinium. 



13. Keel supporting a superstructure, n. 



n. Superstructure of thin oblique subimbricating plates (scalse). 



LI II. Unitrypa. 



n. Superstructure a reticulated network LV. Hemitrypa. 



9* Apertures in more than two rows (rarely two) 14. 



14. No median keel (or row of tubercles) 0. 



0. Apertures in 2 to 8 rows in a branch, frond as in Fenestella. 



LVIII. Polypora. 



0. Apertures in 2 to 5 ranges ; frond supported by non-poriferous 



U- or V-shaped base LX. Lyropora. 



14. A prominent median keel present, with two rows of apertures 



at each side LXI. Feneslralia. 



XX Connecting bars absent or indistinguishable, branches anastomosing. 10*. 

 10* Branches irregularly anastomosing 15. 



15. Two to eight rows of apertures ; reverse side longitudinally stri- 



ated XLVIII. Phylloporina. 



