FOSSIL CORALS OF THE NIAGARA GROUP. 



STEEPTELASMA, Hall. 



Streptelasma ? (Zaphrentis ?) exstans, n. sp. 



Corallum simple, turbinate; diameter of the calix 20mm., depth 20 

 mm., sides regularly and abruptly sloping toward the center, where 

 there is an elevation, having a diameter at the base of 7 mm. and a 

 height of nearly 10 mm.; number of lamellae 74, of nearly uniform size 

 at the margin, alternating below ; on the anterior side is one lamella 

 more developed than the others toward which a few of the adjacent 

 lamellae converge, on each side of, and adjoining this prominent 

 lamella, are four small ones, and on the dextral and sinistral sides of 

 the calix, at equal distances from the anterior ray, are four other 

 small lamellae. 



Formation and locality. Niagara limestone, Milwaukee, Wisconsin. 



Streptelasma? (Zaphrektis) ? limitare, n. sp. 



Corallum simple, turbinate, curved; diameter of the calix 25 mm., 

 depth 20 mm., anterior side nearly vertical; fossette situated poster- 

 iorly, commencing at the center, not extending on the sides ; the 

 extremities of the lamellae coalesce, forming a well defined vertical 

 wall to the fossette ; number of lamellae 70, of uniform size at the 

 margin, alternating below, the principal ones extending to the margins 

 of the fossette. 



Formation and locality. Niagara Limestone, Eacine, Wisconsin. 



PTYCHOPHYLLUM, Edwards & Haime. 



Ptychophyllum ploriforme, n. sp. 

 Corallum simple, turbinate; diameter of the calix 35 mm., depth 10 

 mm,, for a distance of 8 mm, from the margin the sides are gently, 

 then abruptly, sloping toward the center; a space at the bottom 7 mm. 

 in diameter elevated and indented on one side by the fossette, which 

 consists of a shallow pit not extending on the sides of the calix, its 

 [Sen. Doc. No. 38.] 52 



