52 PALyEONTOLOGY. 



OYATHOPHYLLIDiE. 



Genus ZAPHRENTIS, Rafinesque and Clifford. 

 Zaphrentis excentrica, Meek. 



Piate 4, figs. 1, 1 a, 1 6, 1 c, 1 d. 



Corallum obliquely subturbinate, moderately curved, very rapidly ex- 

 panding. Calice apparently shallow, nearly circular, and (at least in the 

 type-specimen) remarkably eccentric on the dorsal or convex side. 

 Septa thin, straight or somewhat curved, about 160 in a specimen 2.50 

 inches in diameter ; every alternate one continued some distance inward, but • 

 not reaching the middle, there being a rather broad, smooth, flat space left in 

 the bottom of the calice ; while those on each side of the fossula converge so 

 as to intersect it before reaching the margin of the smooth central area; 

 secondary series of septa extending but a short distance inward between the 

 others ; all of both series on the dorsal or convex side, as seen in weathered 

 specimens, divaricating upward from a line along the middle on the exterior 

 surface. Fossula well developed, and situated on the dorsal side, but ex- 

 tending inward to the margin of the flattened bottom- of the calice. Outer 

 vesicular area, as seen in a vertical section from the outer to the inner side 

 of the curve through the fossula., comparatively narrow on the dorsal side, 

 but very wide on the inner side, where it is occupied by numerous unequal, 

 rather small, vesicles, ranging obliquely outward and upward within, but 

 curving out horizontally, or even declining a little toward the exterior; 

 tabulge, as seen in the vertical section mentioned above, very thin, closely 

 arranged, numerous, and passing horizontally across from the wide vesicular 

 area, on the inner or concave side of the curve, nearly to the dorsal side, thus 

 occupying more than half the entire breadth of the corallum; somewhat di- 

 vided above, but becoming more simple, straighter, and much more crowded 

 farther down. 



Length of entire corallum, measuring along the outer side of the curve, 

 about 5 inches ; greatest diameter, 2.50 to 3 inches. 



The only specimens of this species in the collection are so much weath- 

 ered that the epitheca, and at places a portion of the outer vesicles, as well as 

 the margins of the calice, have been removed Sections of it, however, 



