ANTHOZOA—HEXACORALLA. 



99 



orifices, and separated by an equal width. Growth in pyriform or 

 subcylindrical club-shaped masses, with a rudimentary peritheca 

 at the conical base. 



In the Niagara beds of Michigan — more commonly in the same 

 beds of Indiana, Kentucky and Tennessee. 



XLVIII. Tetradium Dana. 

 Massive heads composed of numerous long, slender, prismatic 

 and thin- walled corallites, quadrangular or petaloid in section and 



with four primary septa and numerous 

 tabulae. Increases by fission. Ordo- 

 vicic. 



T. fibratum Safford. (Figs. 159, 160.) 



Ordovicic. 

 Septa nearly reaching center; diameter 

 of corallites 0.04 inch. 



In Stones River and Black River of 

 New York, Canada, Tennessee and other localities. 



Fig. 159. Tetradium fibratum. 



Hexameral Corals. 

 XLIX. Parasmylia E. & H. 

 Cylindrical or conical, simple corals with a scar of attachment at 

 the base. Calyx circular, with granular septa and a spongy colu 

 mella. Epitheca absent or rudimentary, and 

 costae strong. Cretacic. 



Fig. 160. Tetradium 

 fibratum, cross-section 

 much enlarged (after 

 Lambe). 



130. P. austinensis Roem. Cretacic. 

 Top-shaped coral attached by a broad 



base, above which it is contracted, strong 

 equal costae. Calyx slightly compressed with 

 septa in four cycles. 



In the Edwards limestone (Lower Cretacic) of Texas. 



131. P. texana Vaughan. (Fig. 161.) Cretacic. 

 Differs from the preceding in having costae alternating large and 



small. 



In the Buda limestone (Lower Cretacic of Shoal Creek, Texas). 



L. Pleurocora E. & H. 



Branching cylindrical corals with a thick compact wall without 

 epitheca. Columella of numerous points (papillose); septa granu- 

 lar, projecting above the calyx. Costae distinctly wavy. Cretacic. 



