ORDER If 



CRYPTOSTOMATA 



'A 1 5 



Escharopora Hall (Nicholsonia Waag. and Wentz) (Fig. 504, a, h). Like Ptilodictya 

 biit apertiires are in diagonally intersecting series. Ordovician. 



Phaenopora Hall. Zoaria as in Ptilodictya^ except that tliere are two mesopores in 

 eacli interspace between tlie ends of tlie zoa3cial apertures. Ordovician and Silurian. 



Ärthropora Ulr. Zoaria bushy, spreading in a plane, composed of numeroiis 

 equal segments. Zooecial apertures elliptical, surrounded by a delicate peristome. 

 Interspaces witb one or more threadlike ridges, varioiisly disposed, and with a row of 

 minute papillae. Ordovician and Silurian. 



Graptodictya Ulr. Ordovician. Clathropora Hall. Silurian. Stictoporina Hall. 

 Devonian. 



Family 7. Stictoporellidae Nickles and Bassler. 



This family differs froni tlie Ptilodictyonidae mainly in that tlie zoarium is not 

 articulated, but grows upward from, and is continuous with, a spreading base. 



Stictoporella Ulr. (Fig. 504, c, d). Zoaria variously formed, wdth elliptical 

 apertures placed at the bottom of a sloping area. Thick-walled intabulated mesopores 

 occur between the zocEcial a])ertures and line the zoarial margins. Ordovician and 

 Silurian. 



Stictopora Hall. Ordovician. Ptilotrypa Ulrich. Silurian. Intrapora Hall. 

 Devonian and Lovver Carboniferous. Coscinella Hall. Devonian. Taeniodictya Ulrich. 

 Devonian and Lower Carboniferous. Heliotrypa Ulrich. Lower Carboniferous. 



Family 



Rhinidictyonidae Ulrich. 



Zoaria bifoliate, continuous or jointed, forming compressed hranches or leaf-like 

 expansions; occasionally trifoliate. Primitive celU sub-quadrate, arranged longitudinally. 

 Both primitive and superficial apertures elliptical or sub-circular, sometimes a little 

 truncated posteriorly. Inferior hemiseptum and lunarium ivanting. Median tubuli 

 present between the median laminae, and between the longitudinal rows of zooecial tubes. 

 Mesopores absent, but vesicular tissue often present. Chiefly Ordovician. 



Rhinidictya Ulr. {Stictopora Ulr., non Hall) (Fig. 505, et, c). Zoaria composed of 



Fig. 505. 



a-c, Rhinidictya mutaUlis Ulr. i/i »nfi surface 9/i. c, Several zooecia »5/j. d, c, Cystalictya gübcrti Meek. 



Surface l8/i and tangential section i8/j (after Ulrich). 



narrow, compressed, dichotomously dividing, straight-edged branches, attached to 

 foreign bodies by a continuous expanded base. Ordovician and Silurian. 



Eurydictya, Dicranopora, Goniotrypa Ulr. Ordovician and Silurian. 



Euspilopora Ulr. Small, irregularly divided branches, with serrated or wavy 

 edges. Devonian. 



