CONTRIBUTION TO 33. 



The specific oame, is in honor of Dr. R. T, Jackson, the eminent Palaeontol- 

 ogist, of Harvard University. 



Found in the upper Devonian (Hamilton group), near Charlestown, Indi- 

 ana. Now in the collection of the author. 



BLOTHROPHYLLUM B E L L I C I N C T UM, N. Sp. 



Plate 11. Figs. 9-10. 



Corallum simple, elongate turbinate, straight or regularly curved. Acute 

 at the base of attachment, gradually or at times, more rapidly expanding in 

 diameter to the calix. Exterior with shallow annulations, and sharp constric- 

 tions, and wrinkles, caused by intermittent growth, Epithica thin ; when de- 

 -corticated it has the appearance of a number of thin invaginated cups, with 

 large oblong vesicles on the surface. Height varying in different individuals, 

 from thirty to one hundred millimeters or more. Calix funnel-shaped, from 

 twenty-five to forty millimeters in diameter. Depth twenty-five to thirty-five 

 millimeters. Number of lamellae seventy, in the circumference of a calix, thir- 

 ty-five millimeters in diameter. Very unequal in size at the margin; 

 alternating in length, the short ones scarcely more than rudimentary; the 

 longer ones are somewhat thick at the margin, growing thinner as they gradu- 

 ally slope to the center of the calix, and terminate. Fossette consists of a 

 -deep depression in the center of the calix, but does not extend far on the side 

 •of the cup. 



The thin wrinkled epithica, and the deep funnel-shaped calix, and the 

 ilarge oblong vesicles, on the exterior, makes this easily recognized from all other 

 species. 



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

 the Ohio. Now in the collection of the author. 



