ORDER III 



TBEPOSTOMATA 



335 



zooecial tul)es ; tlie spaces becoiiie filled up with ag(', l^y a calcareous dei)osit, rendfring 

 walls of inesopores unrecognisable. Ordovician. 



Dianulites Eicliwald (Fig. 485, D). Zoaria massive ; zooccia and mesopores pris- 

 matic, tliin walled ; walls and spines with miniite granulöse stnictures as in 

 Nicholsonella. Ordovician and Silurian. 



Tdiotrypa Ulr. Silurian ; North America. 



Family 4. Batostomellidae Ulrich. ^ 



Zoaria usually ramose, occasionally suh-lobate, massive^ laminar or paradtic, often 

 consisting of superimposed layers. Zocecia tvith thick walls in the mature region^ usually 

 appearing here as fused. Diaphragms horizontal, those in peripheral region with central 

 Perforation. Acanthopores and mesopores usually present; the latter small, often 

 intermittent. Ordovician to Permian. , 



The amalgamate nature of the zooecial walls is most marked in this family. 



Bythopora Miller and Dyer. Small branching stems. Apertures oblique, 

 attenuate above. Interspaces canaliculate, with an occasional mesopore or none. 

 Ordovician and Silurian. 



Gallotrypa Hall. Silurian and Devonian. Eridotrypa Ulrich. Ordovician to 

 Devonian. 



Batostomella Ulr. {Geinitzella W. and W. ; Trematella Hall) (Fig. 486). 



Slender 



Fi(i, 486, 



Batostomella splnulusa Mir. ehester Group ; Kentucky. A, B, Vertical sections, one with and the other 

 without diaphragms, i'i/i. C, Tangential section, l^/j. j)^ Surface, i^/^. On either side of C are branches of the 

 natural size (after Ulrich). 



branches, without monticules. Apertures small, circular or oval. Interspaces 

 rounded or canaliculate, spinulose, the acanthopores small and usually very numerous. 

 Mesopores small, sub-circular. Diaphragms few. Silurian to Permian. 



Stenopora Lonsd. (Fig. 487). Zoaria ramose, sub-lobate, massive, laminar or 

 parasitic. Zooecial walls periodically thickened in the mature region. Large 

 acanthopores at many of the 

 angles between the zooecia. 

 Mesopores never very numerous, 

 irreglüarly distributed. Dia- 

 phragms sometimes very scarce, 

 but in most American species 

 abundant in the peripheral 

 region, and with a large central 

 Perforation. Lower Carboni- 

 ferous to Permian, 



Anisotrypa Ulr, Divisional 

 line between adjoining tubes 

 niorP «bnmlv rlpfiiipd and Ste.nopora ame^^ana V\r. Keokiik Group ; Illinois. Vertical (X) 

 more snarply aennea, ana ^^^ tangential (B) sections showing moniliform walls and perforated 

 periodic SWellingS of the walls diaphragms, l-»/^ (after Ulrich), 



Fi.i. 487. 



