324 MOLLUSCOIDEA— BRYOZOA phylum v 



Family 10. Eleidae d'Oibigny. 



Zoaria ramose, bifoliate or imi-lamellate. Zooecial tubes dilating outivardly, with 

 j^erf orated walls. Apertures lateral and, sub-terminal, many of them dosed by thin 

 calcareous films. Vicarious avicxdaria and spines scattered among the zoacia in some of 

 the genera. Cretaceous. 



The members of this family differ widely from the true Cyclostomata, and the presence of 

 avicularia indicates strong affinities with the Chilostomata. The Eleidae undoubtedly 

 represent connecting links between the Cyclostomata and Chilostomata. The simplest type 

 of Eleid structure is found in the Jurassic genus Ilaploaxia Gregory, now placed in the 

 Entalophoridae, in wlucli the aperture is subterminal, instead of terminal, and is constricted 

 laterally. 



Reftelea d'Orl). Zoariuni adnate, no avicularia. 

 Elea d'Orb. Zoarium erect, bifoliate ; no avicularia. 



Meliceritites Roemer (Inversaria Hagenow ; Escharites Roemer). Cylindrical 

 brandling steins ; avicularia present. 



Foricula d'Orlj. Like Meliceritites but Las walls pierced by pores. 

 Semielea, Nodelea d'Orb. ; Reftoceritites Gregory. 



Suborder B. CANCELLATA Gregory. 



Zooecia monomorphic with \oalls perforated by cancelli, that is, by rounded or elongate 

 pore-like cavities different from the usual interspaces or mesopores. 



This suborder which is more convenient than natural, developed in early Cretaceous 

 times from certain specialised species of the Idmoneidae. 



Family 11. Horneridae Hincks. 



Zoarium erect and branched ; zooecial apertures only on the obverse side and irregular 

 or arranged in simple lines. Walls of zoarium traversed by fine canals luhich appear 

 at the surface as minute pores. Cretaceous to Recent. 



Hornera Lamx. ; Siphodictyum Lonsdale; Hemicellaria d'Orb.; Phormopora Marsson. 



Family 12. Petaloporidae Gregory. 



Ramose Cyclostomata with zooscia opening on all sides of the branches and walls 

 perforated by numerous mural pore structures, somewhat resembling mesopores. 



Petalopora Lonsdale {Cavea d'Orb.) ; Sparsicavea d'Orb. ; Gavaria Hagenow ; 

 Reptocavea d'Orb. Cretaceous and Tertiary. 



Suborder C. DACTYLETHRATA Gregory. 



Cyclostomata with long cylindrical zocecia separated by dactylethra, that is, by short 

 aborted zooecia closed externally. No cancelli, mesopores or avicularia. 



Family 1 3. Clausidae d'Orbigny. 



Zoarium adnate or erect with the zocecia distributed uniformly and separated by 

 circles of shallow interstitial cells (dactylefhrae) closed at the surface. 



Clausa d'Orb. {Claviclausa d'Orb.). Zoarium erect and dendroid. Cretaceous and 

 Tertiary. 



