DESCEIPTIONS OF SPECIES. 



93 



Genus TROOHOCYATHtJS Milne-Edwards and Hairae. 



TBOCHOCYATHTJS HYATTl sp. nov. 



PI. VI, figs. 19 to 21; PI. VII, fig. 1. 



Shape short, trochiforra; cross section circular. Free in adult; on the 

 base a scar as if the corallum were attached in its younger stages. Gran- 

 ular costse corresponding to all of the septa, sometimes obscured by the 

 epithecal deposit. On the upper part of the wall, when not covered by 

 epitheca, they are very distinct; those corresponding to the septa of the 

 first two cycles the largest. Epitheca thick, usually not reaching to the 

 upper margin of the theca. Septa in four cycles, six systems, exsert, 

 especially those of the first two cycles; there are sometimes small septa 

 of the fifth cycle; their surfaces granular and undulate. Those of the 

 third cycle fuse by their inner edges to those of the second cycle. Pali 

 in two crowns, present before the first tlu-ee cycles of septa, undulate, with 

 granular surface. Columella composed of ascending rods or trabeculse 

 which present a papillate upper surface 



Mm. 



Diameter of calice 11.8 



Height of corallum 10 



ilt, 



10 

 8 



Myn. 

 11.8 

 8.5 



Mm 



11 



6 



Localities. — Black Bluff" and Prairie Creek, Alabama. 



Geologic occurrence. — Black Blufi" (Sucamocliee) beds. 



Types. — United States National Museum. 



The following additional notes on the septa may be added: The septa 

 are composed of ascending trabeculcTe, which possess a line of divergence. 

 The courses of the trabeculse are indicated by rows of granules. The 

 rows of granules do not stand opposite one another on opposite sides of the 

 septum, but alternate in position. The septal margins are usually entire or 

 nearly so, but occasionally the trabeculse project slightly on the margin 

 and make obscure dentations, especially on the septa of the higher cycles 

 near the wall. The costse are serrate or granulate. Near the places of 

 fusion of septa by their margins to the sides of lower cycles synapticulse 

 sometimes occur. The wall seems to be formed by the fusion of the distal 

 ends of the septa, or it may be an eutheca. 



