ORDER III 



TREPOSTOMATA 



335 



zooecial tuljcs ; tlie spaces become filled up with age by a calcareous deposit, rendering 

 walls of inesopores unrecognisable. Ordovician. 



Dianulites Eichwald (Fig. 485, D). Zoaria massive ; zocccia and mesopores pris- 

 matic, ttin walled ; walls and spines with minute granulose structures as in 

 Nicholsonella. Ordovician and Silurian. 



Tdiotrypa Ulr. Silurian ; North America. 



Family 4. Batostomellidae Ulrich. 



Zoaria usually ramose, occasionally sub-lobate, massive, laminar or parasitic, often 

 consisting of superimposed layers. Zocccia with thick walls in the mature region, usually 

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

 Devonian. 



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



1 l/fft 



Ordovician to 

 Slender 



Large 



Fl(i. 486. 



Batostomella splnidosa Ulr. Chester Group ; Kentucky. A, B, Vertical sections, one with and the other 

 without diaphragms, n/i- C, Tangential section, i^i- D, Surface, I'l/j. On either side of (.' are branches of the 

 natural size (after Ulrich). 



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

 rounded or canaliculatej spinulose, the acanthojDores 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 

 acanthopores at many of the 

 angles between the zooecia. 

 Mesopores never very numerous, 

 irregularly distributed. Dia- 

 phragms sometimes very scarce, 

 but m 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 Fn;. 487. 



iiir.TP cliarnW rlpfinprl mid Stenopora americana Vlv. Keokuk Group ; Illinois. Vertical (.4) 

 moie sudipiy uemieu, ciiiu ^nd tangential (Z;) sections showing roonilifonu waUs and perforated 



periodic swellings of the walls diaphragms, w/j (after Ulrich), 



