276 W. jr. SHERZER — THE GENUS CKONOPHYLLUM. 



center without any decided twisting. They are roughly granulose on 

 the upper surfaces, sharp in and about the pit, hut toward the outer area 

 becoming broad and convex, attaining a width of 1.5 mm and leaving 

 narrow interseptal grooves. These septa are formed of curved layers, 

 convex upward, which are typically deflected downward at their edges 

 to form the side face-, but which frequently pass into the poorly defined 

 interseptal cavities and abut against those of adjoining septa. Com- 

 pared with C. magnificwn, they are coarser and more distant in propor- 

 tion to the size of the septum and less strongly curved. Apparently in 

 corresponding position, they give an appearance of invaginated cell- 

 cups to the corallum. Vertical tangential sections show at times a central 

 radial supporting plate, extending upward through a number of layers, 

 very suggestive of that to be described for Oyathophyllum helianthoides. 

 These plates may be double, branching and irregular. Radial sections 

 through the septa show the edges of these layers curving upward and 

 outward, intersected by the supporting growths, and forming elongated, 

 flat vesicles somewhat as in the preceding species. Between these 

 septal plates more delicate vesicles are interposed, so that in grinding 

 down such sections it is not easy to tell where the interseptal cavity 

 ends and the septum begins. 



The central part of the corallum has been dissolved and only the 

 outer silicified portion remains, so that the central structure cannot be 

 studied so thoroughly as desired. The vesicles are well developed, a< 

 shown in radial sections through the interseptal cavities and in vertical 

 tangential sections uniting the septa. They are irregular in size and 

 arranged in curved rows inclining upward and outward. In grind- 

 ing the specimen down and examining it at the successive stages, it was 

 found that no well defined tabulae are present. Transverse leaflets, con- 

 cave upward or flat, are placed in the wedge-shaped interseptal cavities, 

 and rather closely approximated. When placed ;it approximately the 

 same height in neighboring cavities they simulate irregular tabulae for 

 short distances. 



Formation and locality: Niagara limestone, Beargrass creek, near 

 Louisville, Kentucky. 



Tins species is less turbinate and expanded than other forms of Chono- 

 phyllum. Its shape is more suggestive of the larger, conico-eylindrical 

 forms of C. magnificum. It is readily distinguished from the3e by the 

 irregularities in the septal structure, the layers being coarser, more dis- 

 tant and less curved. f 



Nearest Relatives. 



General Relations. — The separation of this genus from those closely 

 related to it. and most liable to be mistaken for it. becomes a matter of 



