47. CONTRIBUTION TO 



in diameter. Situated in the center of the calix is an elevation, formed by the 

 elevated tabulae, five millimeters in height. Number of lamellje sixty, in the 

 circumference of a calix, thirty millimeters in diameter, unequal in size at the 

 margin, and alternating in length, for about ten millimeters, gradually, then 

 rapidly slope to the bottom of the calix, where the short ones terminate, the 

 longer ones become elevated, and thinner, as they continue to the bottom of the 

 calix. Coalescing and twisting into a sharp crest on the elevated tabulae. 



In a great number of examples examined, I have failed to discover any trace 

 of a fossette. 



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

 Ohio, Now in the collection of the author. 



HELIOPHYLLUM ROWLEYI, N. 8p. 



Plate 16. Fig. 1. 



Corallum simple, elongate turbinate, or conico-cylindrical, straight or irregu- 

 larly curved, or distorted. Acute, or in some examples, they have a broad scar, 

 at the base of attachment, and occasionally, an example will have slender 

 root-like processes near the base, for attachment, to foreign objects for support. 

 Gradually, or at times, rapidly expanding in diameter to the calix. Height 

 varying in different individuals, from six to fourteen inches or more. Calix 

 broadly bell-shaped, thirty millimeters in diameter. Depth twenty-five millime- 

 ters, a smooth convex space in the bottom of the calix occupied by the tabulae, 

 fifteen millimeters in diameter. Number of lamellae ninety, in the circumfer- 

 ence of a calix, thirty millimeters in diameter, alternating in size, the small 

 ones merely rudimentary ; the longer ones for about ten millimeters, gradually 

 slope, then abruptly turn down, and continue until they reach the tabulae, leav- 

 ing a smooth convex space in the bottom of the calix, ten millimeters in diame- 

 ter. Exterior when decorticated has a very rugose appearance. Situated at 

 somewhat regular intervals, there are funnel-shaped expansions, giving to the 

 corallum, somewhat the appearance of a number of invaginated funnels. The 

 lamellae on these funnel-shaped expansions, are uniform in size, and length, and 

 the denticulations are much finer than those in the calix. Fossette consists of 

 a slight depression on the anterior side of the tabulae, but disappears before 

 reaching the margin of the calix. 



The specific name is in honor of Prof. R. R. Rowley, of Louisiana, Mo. 



Found in the lower Devonian (Corniferous group), at the Falls of the Ohio. 

 Now in the collection of the author 



