424 Thirty- fifth Report on the State Museum. 



ing ones much stronger than the others, and continuing nearly to the 

 center of the calix, which is smooth and concave. This species most 

 nearly resembles Zaphrentis prolifica, but the center of the calix is 

 depressed, while that of prolifica is always more or less convex, with 

 distinct tabulae. 



Formation and locality. Corniferous limestone, Canada West. 



Streptelasma crateriforme, n. sp. +/ .2-f£ fi+ 6X/* 



Corallum simple, turbinate, curved, acute at the base, regularly ex- 

 panding to the calix; longitudinal striae distinct, 12 in the space of 

 5 mm. ; height of corallum 40 mm.; diameter of the calix 30 mm., 

 depth 20 mm., walls very thin ; fossette sinistral, commencing near 

 the center and continuing to the margin, moderately conspicuous ; 

 number of lamellae from 80 to 90, alternating in size, near the margin 

 thickened and angular, very thin below. The principal lamellae con- 

 tinue to the center, twisting and coalescing, but not elevated ; the 

 margins of the lamellae are finely denticulated. The characteristics of 

 this species are the deep calix and the thin walls. 



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



Streptelasma involutum, to. sp.J > J,X^'F/ff>.9, 

 Corallum simple, turbinate, exterior with undulations of growth 

 and concentric striae ; longitudinal striae distinct ; height of cor- 

 allum 40 mm.; diameter of calix from 15 to 20 mm., depth 20 mm., a 

 space at the center 3 mm. in diameter depressed; fossette situated an- 

 teriorly; number of lamellae from 50 to 60, alternating in size, the 

 larger ones extending to the center, twisting, coalescing and depressed. 

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



Streptelasma aequidistans, n. sp. /V £>^ /> * / ' *•// 



Corallum simple, turbinate, base acute, more or less regularly ex- 

 panding to the calix, height 30 mm.; diameter of the calix 25 mm., 

 depth 20 mm., sides abruptly and regularly sloping to the center; 

 fossette commencing near the center and extending about half way to 

 the margin, number of lamellae from 90 to 100, alternating in size, at 

 the margin,thickened and angular, becoming very thin and sharp as 

 they approach the center. At equal distances from the fossette on each 

 side . there are two lamellae continuing to the center; the adjacent 

 lamellae on one side converge to these ; the remaining principal 

 lamellae continue to the center ; on the sides of the lamellae rec- 

 tangular to the margins are very fine obscure striae, and the margins 

 are obscurely crenulated. 



Formation and locality. Corniferous limestone, New York. 



