ss. CONTRIBUTION TO 



HELIOPHYLLUM, COLLATUM. N. Sp. 



Plate 20. Figs. 4-5-6-7. 



Corallum simple, or composite, increasing by lateral gemmation. In some 

 examples the tubes are round, the margins free, or slightly in contact by their 

 epitheeal walls. In some other corrallumns the cup margins are intimately con- 

 nected in polygonal outlines. Diameter of corallites varies in different exam- 

 ples, and even in the same corallum, from five to fifteen millimeters. Depth 

 from five to ten millimeters. Situated in the center of the calix is a 

 smooth concave space, occupied by the tabulse, five millimeters in diameter. 

 Number of lamellae forty-eight, in the circumference of a calix ten millimeters 

 in diameter, equal in size at the margin, alternating below; gradually, or at 

 times rapidly sloping to near the bottom of the calix, where the short ones 

 gradually disappear ; the longer ones continue to the margin of the smooth, 

 concave space, and abruptly terminate. Denticulations fine, ten in the space 

 of three milimeters. Exterior of corallites somewhat rugged, with annulations 

 and wrinkles, and coarse, longitudinal strite. No fossette observed in any of 

 the cups. 



Found in the middle Devonian (Upper Helderberg group) at the Falls of 

 the Ohio, now in the collection of the author. . 



HELIOPHYLLUM, HA MM ELL I. N. Sp. 



Plate 20. Figs. 1-2-3. 



Corallum composite, rapidly increasing, by calicular or lateral gemmation. 

 Tubes rounded or polygonal, unequal in size, from five to seventeen millimeters 

 in diameter. Depth seven to ten millimeters. Situated in the bottom of the M 

 calix is a smooth flat, or sometimes a concave space, occupied by the tabulse, ^ 



from five to seven millimeters wide. Stems rather lax in some places ; in this 

 case they are rounded, in other portions they are more intimately connected, and 

 the ends of the tubes are Joined in polygonal outline. Number of lamellas sixty, 

 in the circumference of a calix, seventeen millimeters in diameter; equal in size 

 at the margin, alternating below, for about five millimeters from the margin, 

 flat or slightly oval, then abruptly slope to the bottom of the calix, where the 

 short ones gradually terminate, the longer ones continue to the margin of the 

 smooth space in the center of the calix, and abruptly ends, leaving a smooth 

 space in the center of the calix, from five to seven millimeters in diameter. 

 Denticulations fine, ten in the space of six millimeters. No fossette visible in 

 any of the cups. 



The specific name is in honor of Mr. John Hammell, of Madison, Indiana. 



Found in the middle Devonian (upper Helderberg group) at the Falls of 

 the Ohio. Now in the collection of the author. 



