39. CONTRIBUTION TO 



This species is easily recognized from Cyathaxonia Cynodon of (Rafinesque and 

 Clifford), by the absence of spines, and being more regularly curved. 



Found by Prof. W. W. Borden, in whose honor the specific name is given, 

 in the Knobstone group (Sub-carboniferous) at Stone's Farm, one and a half 

 miles east of Bridgeport, Clark county. Indiana. Now in the collection of the 

 author. 



CYATHAXONIA PARVA, N. Sp. 



Plate 14. Figs. 7-8-9. 



Corallum simple, turbinate, regularly curved. Acute at the base of at- 

 tachment, gradually, and regularly expanding in diameter to the calix. Exte- 

 rior comparatively smooth, with a few shallow undulations of growth. Longi- 

 tudinal strite rather fine, distinct, ten in the space of five millimeters. Height 

 thirty millimeters. Diameter of calix ten millimeters. Depth five millimeters. 

 Walls nearly vertical. A smooth conical elevation in the center of the calix, 

 two millimeters in diameter at the base, and three millimeters in height. Num- 

 ber of lamellse fifty, in the circumference of a calix ten millimeters in diameter, 

 unequal in size, and sharp at the margin, alternating below, rapidly descends to 

 the bottom of the calix, where the short ones terminate ; the longer ones con- 

 tinue to the margin of the conical area, in the bottom of the calix, and abrupt- 

 ly end, leaving the conical elevation smooth. No fossette visible in any of the 

 examples examined. 



The numerous sharp and unequal lamellae, and more robust form, and 

 somewhat larger calix, makes this easily recognized from all other species. 



Found in the Knobstone group (sub-carboniferous), at Stone's Farm, one 

 and a half miles east of Bridgeport, Clark county, Indiana. Now in the collec- 

 tion of the author. 



PTYCHOPHYLLUM ROBUSTUM, N, Sp, 



Plate 14. Figs. 1-2. 



Corallum simple, turbinate, straight or regularly curved. Acute at the 

 base of attachment. Gradually or in some examples rapidly increasing in di- 

 ameter to the calix. Exterior with a thick, comparatively smooth epithecal 

 crust, and rather distant, shallow annulations, more strongly pronounced on 

 the anterior side. Height varying in different individuals, from seventy, to 

 one hundred and twenty millimeters. Calix broad, bell-shaped, from thirty- 



