7 6 



NORTH AMERICAN INDEX FOSSILS. 



In the Hamilton beds of New York, Canada, Michigan, etc. 

 Also in Devonic limestones of Ohio. 



60. C. subcaespitosum (Nicholson). Devonic. 

 Smaller than the preceding, of long slender stems increasing 



chiefly by lateral gemmation. Septa more numerous and more 

 closely crowded than in the preceding, strongly carinated. Inner 

 wall often closed in the adult. 



Common in the Hamilton beds of New York, Canada and 

 Michigan. 



XXVI. Duncanella Nicholson. 



Coral slender, resembling Streptelasma, with radial septa, and a 

 strongly developed epitheca which, however, is absent at the base 

 of the corallum, where the septa are visible. 

 Siluric. 



61. D. borealis Nicholson. Siluric. L 

 Small, slender, and scarcely over half an 



inch in length. Costae well developed. 



In the Niagara group of Indiana and else- 

 where. 



XXVII. LOPHOPHYLLUM E. & H. 



Corallum zaphrentoid, but with a central 

 compressed columella often continuous on 

 one side with the cardinal septum. Carbonic. 

 62. L. profundum (E. & H.). (Fig. 1 19.) 



Carbonic. 



Curved, horn-like corallum, with septa from 

 30 to 50 alternating in length. Columella 

 striated. Length of average individual 30 

 mm., width of calyx 9 mm. 



In the coal measures of Iowa, Illinois 

 Texas, etc. 



XXVIII. Lithostrotion Lhwyd. 



Heads composed of prismatic or cylindrical corallites, each 

 enveloped by an epitheca and all by a peritheca. Central portion 

 occupied by tabulae which are inverted funnel-shaped, terminating 

 in the calyx in a pseudo-columella. Septa well developed, outer 

 area with numerous dissepiments. Carbonic. 



FlG. 119. Lophophyl- 

 lum profundum (Ind. 

 Geol. Survey). 



Kansas, Nebraska, 



