106 THE PALEONTOLOGY OF MINNESOTA. 



[Classification. 



Family PTILODICTYONID.E, Zittel. 



Genera : Ptilodictya LONSDALE, Clathropora HALL, Phmiopora HALL, Graptodictya ULRICH, Arthro- 

 pora U., TceniodictyaU., Ptilotrypa U., Stictotrypa'C., StictoporellaV., Intrapora HALL, Coscinella HALL. 



Family KHINIDICTYONID^E, Ulrich. 



Genera: Rhinidictya ULRICH, Eurydictya U., Dicranopora U., Ooniotrypa U., Euspilopora U., Pfiyl- 

 lodictya U., Pachydictya U., Stictopora HALL. 



Family CYSTODICTYONIDJE, Ulrich. 



Genera: Cystodictya ULRICH, Coscinium KEYSERLING, Dichotrypa U., ActinotrypaU ., Tceniopora 

 NICHOLSON, Prismopora HALL, Scalaripora HALL, Evactinopora MEEK and WORTHEN, Olyptopora U., 

 Goniocladia ETHRIDGE, Acrogenia HALL. 



Family RHINOPORIDJE, Ulrich. 

 Genus : Rhinopora HALL. 



Family HELIOTRYPID^E, Ulrich. 

 Genus : Heliotrypa ULRICH. 



Family ARTHROSTYLITXE, Ulrich. 



Genera : Arthrostylus ULRICH, Helopora HALL, Sceptropora ULRICH, Arthroclema BILLINGS, Nema- 

 topora ULRICH, f Thamnotrypa HALL. 



Family RHABDOMESONTID^:, Vine. 



Genera: Rhabdomeson YOUNG and YOUNG, Cceloconus ULRICH, Rhombopora MEEK, Nemataxis 

 HALL, Acanthoclema HALL, Bactropora HALL, ? Tropidopora HALL. 



Family STREBLOTRYPID^, Ulrich. 

 Genera: Streblotrypa ULRICH, Cyclopora PROUT, PProutella ULRICH, PCycloporellaU. 



Family SPHRAGIOPORID^K, Ulrich. 

 Genus : Sphragiopora ULRICH. 



Family FENESTELLIDJE, King. 



Genera : Fenestella LONSDALE, Semicoscinium PROUT, Fenestrapora HALL, Isotrypa HALL, Tectuli- 

 pora HALL, Unitrypa HALL, Hemitrypa PHILLIPS, Helicopora CLAYPOLE, Archimedes LESUEUR, Lyropora 

 HALL, Fenestralia PROUT, Polypora McCoY, Thawiniscus KING, Phyllopora KING, Ptiloporina HALL, 

 Ptiloporella HALL, t Loculipora HALL. 



Family ACANTHOCLADIID^S;, Zittel. 



Genera : Pinnatopora VINE, Septopora PROUT, Acanthocladia KING, Synocladia KING, Diplopora 

 YOUNG and YOUNG, Ptilopora McCOY, f Icthyorachis McCoY, ? Penniretepora d'ORBlGNY, ? Ramipora 

 TOULA. 



Family PHYLLOPORINIDJK, Ulrich. 



Genera : Phylloporina ULRICH, Chainodictyon FOERSTE, Drymotrypa ULRICH, t Crisinella HALL. 



Suborder TEEPOSTOMATA, Ulrich. 



Zooecia superimposed directly one upon bhe other so as to form long tubes 

 intersected by straight or curved partitions (diaphragms and cystiphragms), repre- 

 senting the covers and floors of the successive layers. Two regions are distinguish- 

 able in the tubes, an axial or "immature" region in which the diaphragms are 

 remote and the walls thin and prismatic ; and a peripheral or "mature " region in 

 which the walls are thickened and otherwise changed, the transverse partitions 

 more abundant, and accessory elements, such as mesopores and acanthopores, devel- 

 oped. Zocecial covers with a small central orifice. 



Family MONTICULIPORIDJS, Nicholson. 



Genera : itonticulipora d'ORBlGNY, Atactoporella ULRICH, Homotrypella ULRICH, Peronopora NICH- 

 OLSON, Homotrypa U., Prasopora NICHOLSON and ETHHIDGE, Mesotrypa U. 



