106 THE PALEONTOLOGY OF MINNESOTA. 
(Classification. 
Family PTiLopIcTyONID&, Zittel. 
Genera: Ptilodictya LONSDALE, Clathropora HALL, Phenopora HALL, Graptodictya ULRICH, Arthro- 
pora U., Teniodictya U., Ptilotrypa U., Stictotrypa U., Stictoporella U., Intrapora HALL, Coscinella HALL. 
Family RHINniicryonip®, Ulrich. 
Genera: Rhinidictya ULRicH, Eurydictya U., Dicranopora U., Goniotrypa U., Euspilopora U., Phyl- 
lodictya U., Pachydictya U., Stictopora HALL. 
Family Cystopicryonip ©, Ulrich. 
Genera: Cystodictya ULRICH, Coscinium K®rYSERLING, Dichotrypa U., ActinotrypaU., Toeniopora 
NICHOLSON, Prismopora HALL, Scalaripora HALL, Evactinopora MEEK and WoRTHEN, Glyptopora U., 
Goniocladia BYHRIDGE, Acrogenia HALL. 
Family RaINoPpoRID#, Ulrich. 
Genus: Rhinopora HALL. 
Family HELIOTRYPID®, Ulrich. 
Genus: Heliotrypa ULRICH. 
Family ARTHROSTYLID®, Ulrich. 
Genera: Arthrostylus ULRICH, Helopora HALL, Sceptropora ULRICH, Arthroclema BILLINGS, Nema- 
topora ULRICH, ’ Thamnotrypa HALL. 
Family RHABDOMESONTID&, Vine. 
Genera: Rhabdomeson YOUNG and YouNG, Celoconus ULRIcH, Rhombopora MEEK, Nematazxis 
HALL, Acanthoclema HALL, Bactropora HALL, ? Tropidopora HALL. 
Family STREBLOTRYPID®, Ulrich. 
Genera: Streblotrypa ULRICH, Cyclopora Prout, ? Proutella ULRICH, ?Cycloporella U. 
Family SPHRAGIOPORID®, Ulrich, 
Genus: Sphragiopora ULRICH. 
Family FENESTELLID®, King. 
Genera: Fenestella LONSDALE, Semicoscinium Prout, Fenestrapora HALL, Isotrypa HALL, Tectuli- 
pora HALL, Unitrypa HALL, Hemitrypa ParLures, Helicopora CLAYPOLE, Archimedes LESUEUR, Lyropora 
HALL, Fenestralia Prout, Polypora McCoy, Thamniscus Kina, Phyllopora KinG, Ptiloporina HALL, 
Ptiloporella HALL, ? Loculipora HALL. 
Family ACANTHOCLADIID®, Zittel. 
senera: Pinnatopora VINE, Septopora Prout, Acanthocladia Kine, Synocladia Kine, Diplopora 
YoOuNG and YouneG, Ptilopora McCoy, 2? Icthyorachis McCoy, ? Penniretepora d’ORBIGNY, ? Ramipora 
TOULA. 
Family PHyLLOPORINID®, Ulrich. 
Genera: Phylloporina ULRICH, Chainodictyon FOERSTE, Drymotrypa ULRICH, ? Crisinella HALL. 
Suborder TREPOSTOMATA, Ulrich. 
Zocecia superimposed directly one upon the other so as to form long tubes 
intersected by straight or curved partitions (diaphragms and ecystiphragms), 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 MONTICULIPORID =, Nicholson. 
Genera: Monticulipora WORBIGNY, Atactoporella ULRICH, Homotrypella ULRICH, Peronopora NICcH- 
OLSON, Homotrypa U., Prasupora NICHOLSON and ETHRIDGE, Mesotrypa U. 
