Niagara Group. 415 



wrinkles and rounded annulations ; when exfoliated the exterior has 

 a somewhat vesicular appearance ; height of corallum from 40 to 50 mm. ? 

 diameter of the calix from 15 to 20 mm., depth 10 mm., a space at the 

 bottom from 8 to 10 mm. in diameter flat, indented on the posterior 

 margin by the fossette, which consists of a narrow, deep pit not ex- 

 tending on the side of the calix ; number of lamellae from 60 to 70, 

 of nearly uniform size at the margin, decidedly alternating below, the 

 principal ones extending to the center, where they are sometimes 

 slightly twisted, often only faintly- indicated on the tabulae at the bot- 

 tom of the calix. 



Formation and locality. Niagara group, Oharlestown, Indiana. 



Zaphrentis subvada, n. sp. 



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

 depth 15 mm., a space at the bottom 15 mm. in diameter convex, in 

 the center of which is an elongate elevation having a height of 4 mm.; 

 tabulae broad; number of lamellae 84, decidedly alternating in size, 

 the smaller ones being about one-fourth the thickness of the others 

 which fasciculate and coalesce, a few of them extending to the center and 

 apparently forming the crest-like elevation at the bottom of the calix. 



Formation and locality. Niagara limestone, Kacine, Wisconsin. 



AMPLEXUS, Sowerby. 



Amplbxus untforme, n. sp. ■ 



Corallum simple, diameter of the calix 15 mm., depth 15 mm., flat 

 for a distance of 2 mm. from the margin, then vertical; tabulae broad, 

 the bottom flat and smooth ; number of lamellae 30, of uniform size, 

 crenulated, extending to the flattened space at the bottom. 



Formation and locality. Niagara limestone, Port Byron, Illinois. 



Amplexus justctum, n. sp. 



Corallum simple, diameter of the calix 8 mm., depth 18 mm., sides 

 vertical, number of lamellae 26, of uniform size, their margins finely 

 denticulated ; between the lamellae are transverse dissepiments, 12 in 

 the space of 5 mm. This species is very similar to A. uniforme, but 

 the depth is proportionally much greater and the lamellae are more 

 closely arranged. 



Formation and locality. Niagara limestone, Port Byron, Illinois. 



CYATHAXONIA, Michelin. 

 Cyathaxonia columellata, n. sp. 

 Corallum simple, turbinate, slightly curved ; diameter of the calix 

 20 mm., oxpth 15 mm.; fossette inconspicuous or obsolete ; a space at 



