ORDKR IV 



CRYPTOSTOMATA 



345 



Escharopora Hall (NicJiolsonia Waag. and Wentz) (Fig. 504, «, h). Like Ptilodictya 

 but apertures are in diagonally intersecting series. Ordovician. 



Phaeiwpora Hall. Zoaria as in Ptilodictya, except that there are two mesopores in 

 each interspace between the ends of the zocecial apertures. Ordovician and Silurian. 



Arfhro'pora Ulr. Zoaria Ijushy, spreading in a plane, composed of numerous 

 equal segments. Zocecial apertures elliptical, surrounded Ijy a delicate jieristome. 

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

 minute papillae. Ordovician and Silurian. 



Graptodictya Ulr. Ordovician. Glathroporu Hall. Silurian. Stictoporina Hall. 

 Devonian, 



Family 7. Stictoporellidae Nickles and Bassler. 



This family differs from the Ptilodictyonidae mainly in that the zoarium is not 

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



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

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

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

 Silurian. 



Stictopora Hall. Ordovician. Ptilotrypa Ulrich. Silurian. Intraponi Hall. 

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

 Devonian and Lower Carbonifei'ous. Heliotrypa LTlrich. Lower Carboniferous. 



Family 8. Rhinidictyonidae L^lrich. 



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

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

 Both primitive and superficial apertures elliptical or snb-circnlar, sometimes a little 

 truncated piosteriorly. Inferior hemiseptum and lunarium wanting. Median tubuli 

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

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



Rhinidictija Ulr. {Stictopora Ulr., non Hall) (Fig. 505, a, c). Zoaria composed of 



Fu:. 505. 



a-c, Rhinidictya mutabiUs Ulr. i/j and surface 9/j. c, Several zocecia »5/]. d, c, Cystodictya gilbcrti Meek. 

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



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

 foreign Ijodies by a continuous exjianded base. Ordovician and Silurian. 



Eurydictya, Bicranopora, Goniotrypa Ulr. Ordovician and Silurian. 



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

 edges. Devonian. 



