Upper Helderberg Group. 435 



and fasciculating, the lamellae thus formed again fasciculating and 

 extending to the center, where they are twisted and elevated into a 

 comparatively sharp crest. The quadrilateral form, convex tabulae, 

 deep fossette and fasciculated lamellae are characteristics by which 

 this species may be easily distinguished. 



Formation and locality. Corniferous limestone, Falls of the Ohio. 



Zaphrentis profunda, n. sp. 



Corallum simple, elongate turbinate, curved ; exterior with numer- 

 ous annulations; external striae fine, distinct; height of corallum 

 70 mm.; diameter of the calix 25 to 35 mm., depth 25 to 40 mm.; 

 there is usually a flat space at the bottom of the calix from one- 

 half to three-fourths the diameter of the corallum at that point, but 

 this feature is sometimes obsolete ; number of lamellae from 100 to 

 110, alternating in size, thickened at the margin, thin and sharp below 

 the principal lamellae extending to within 5 mm. of the center, coalescing 

 with the tabulae and leaving a smooth, nearly flat, space of 10 mm. in 

 diameter. The proportional length and diameter is variable, individ- 

 uals having calices of the same diameter varying in length from 35 

 to 80 mm. 



Formation and locality. Corniferous limestone, Falls of the Ohio. 



Zaphrentis nitida, n. sp. 



Corallum simple, elongate turbinate, straight or slightly curved, ex- 

 terior with numerous quite sharp annulations and constrictions caused 

 by intermittent growth ; external striae very distinct ; height of coral- 

 lum 80 mm.; diameter of the calix 35 mm., depth 20 mm., somewhat 

 campanulate, a space at the bottom from 10 to 15 mm. in diameter 

 smooth, nearly flat; fossette consisting of a deep pit, its continuation 

 extending on the sides but becoming obsolete before reaching the 

 margin of the calix ; number of lamellae from 75 to 90, of nearly uni- 

 form size, thickened and rounded at the margin, becoming thin and 

 alternating below ; the principal lamellae extend a short distance on 

 the tabulae, coalescing with it, not twisted. This species most closely 

 resembles Z. profunda, but is a more solid form and the calix is not 

 so deep. 



Formation and locality. Corniferous limestone, Falls of the Ohio. 



Zaphrektis frequent at a, n. sp. 

 Corallum simple, turbinate, curved ; diameter of the calix 35 mm., 

 depth 30 mm., the bottom of the cup formed by the tabulae is convex, 

 about 20 mm. in diameter ; the fossette consists of a deep depression 

 near the dextral margin of the tabulae, not extending on the side of 

 the calix ; number of lamellae from 90 to 100, alternating in size, the 



