456 Thirty-fifth Beport ok the State Museum. 



structure is as follows : a central area occupied by the flat portion of 

 the tabulae ; the tabulae turn upward and for a distance of 10 or 15 

 mm. are nearly vertical, forming a cylindrical cavity, then turning 

 outward and downward ; in one individual the flat portion of 

 the tabulae is 8 mm. in diameter ; a space 30 mm. in diameter 

 is occupied by the tabulae and lamellae without intermediate structure ; 

 then occur small intermediate cysts whose direction is toward 

 the margin, and the heliophylloid rays, having a direction toward the 

 center ; the outer area consists of a series of the projecting margins of 

 the invaginated calices, the lamellae of which have, on their sides and 

 margins, prominent rays and denticulations, but no vesicles. A calix 

 40 mm in diameter slopes quite abruptly to the depth of 15 mm., it 

 is then flat for a space of 8 mm., then abruptly turns downward and 

 continues vertically for a distance sometimes of 30 mm.; transverse 

 section of the latter portion usually oval ; number of lamellae from 90 

 to 100, alternating in size, the larger ones continuing to the center of 

 the cup, though somewhat obscured on the lower portion of the ver- 

 tical wall ; denticulations prominent, 6 or 7 in the space of 5 mm.; on 

 the sides of the lamellae are oblique, coarse, rounded striations ; these 

 end abruptly at two conspicuous longitudinal grooves, from which to 

 the outer area, a space of about 5 mm., are numerous small cysts ; on 

 the outer area are prominent heliophylloid striae. 



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



Heliophyllum sordidum, n. sp. 



Corallum small, simple, turbinate, height from 15 to 20 mm., diam- 

 eter of the calix equal to the height. Numerous individuals of this 

 species have been observed, but they are invariably decorticated and 

 the margins of the calix broken away, so that its true form cannot be 

 accurately determined ; a conspicuous fossette extends from near the 

 center to the anterior margin ; frequently, along the middle of the 

 fossette, there is a prominent lamella; number of lamellae from 80 to 

 90, alternating in size, the larger ones thick, fasciculating, coalescing 

 and extending to the center, where they are twisted. Owing to the 

 breaking away of the lamellae near the margin the denticulations sel- 

 dom appear; it is, however, easily recognized as a Heliophyllum 

 from the character of the internal costae. 



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



Heliophyllum dehticulatum, n. sp. 

 Corallum simple, turbinate, curved, sometimes in more than one 

 direction; exterior with numerous concentric wrinkles and fine striae ; 

 external costae coarse, prominent; height of corallum ^ 45 mm.; 



