Upper Helderberg Group. 431 



Zaphrentis cyathiformis, n. sp. J*!**- ty zjrj. 



Corallum simple, turbinate, straight or curved, exterior with gentle 

 undulations, comparatively smooth; longitudinal striations distinct;, 

 height of corallum 50 mm., base attenuate; diameter of calix 25 mm., 

 depth 20 mm., sides abruptly descending, a space at the bottom flat, 15 

 mm. in diameter ; fossette extending from flat space to sinistral mar- 

 gin; number of lamellae 80, alternating in size, near the margin thick- 

 ened, becoming sharp on the sides. 



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



Zaphrentis ponderosa, n. sp. 1?1%S, F/* *{-, 

 Corallum simple, turbinate, curved and oblique, exterior with strong 

 rounded ridges, longitudinal striations obscure ; height of corallum 

 100 mm,; diameter of calix 45 mm., depth 35 mm., with a rounded 

 elevation of 15 mm. in diameter at the bottom; number of lamellae 

 90, of nearly uniform size, thickened and rounded at the margin, alter- 

 nating below and becoming thin and sharp as they approach the cen- 

 ter. A portion of the lamella extend to the center, twisting and coa- 

 lescing with the elevated portion of the tabulae. 

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



Zaphrektis tabulata, n. sp. T/xfr 7lq 3xM* 

 Corallum simple, cylindrical, elongate, in a fragment 17 centimetres 

 long there is no increase in the diameter ; exterior with abruptly 

 rounded annulations situated at quite regular distances apart, 9 or 10 

 in the space of five mm.; tabulae numerous, strong, extending nearly 

 to the epitheca, central portion depressed, margins bending downward ; 

 diameter of calix 30 mm., a space at the center 10 mm. in diameter 

 depressed, smooth ; number of lamellae from 80 to 90, the larger ones 

 extending to the smooth space at the center. This species is easily dis- 

 tinguished by its elongated cylindrical form and its regularly annn- 

 lated exterior, which closely resembles an Orthoceras. 



Formation and locality. Oorniferous limestone, Falkirk, Erie Co., 

 K Y. 



Zaphrentis corrugata, n. sp.^t >$,ViAS~y£> 

 Corallum simple, turbinate, curved ; exterior with numerous an- 

 gular ridges of growth ; longitudinal striae fine, very prominent, on the 

 ridges frequently appearing as nodes ; height of corallum 40 mm.; dia- 

 meter of calix 20 mm., depth 15 mm., sides nearly vertical, leaving a 

 flat space at the bottom 12 mm. in diameter ; number of lamellae 70, 

 alternating in size, the smaller ones about one-third the thickness of 

 the others, which extend on the flat space at the bottom, coalescing 



