208 FOSSIL CORAL REEF. [CHAP. XXXV. 



and the valves of a Unio, both of living species ; yet with them 

 were included in the same gravelly and shelly mass, the well- 

 preserved bones of the megalonyx. 



The coal-measures had given place to an older series of strata, 

 the Devonian, when we reached the Falls of the Ohio, at Louis 

 ville, where we saw the river foaming over its rocky bed. I 

 first landed at New Albany, in Indiana, nearly opposite Louis 

 ville, that I might visit Dr. Clapp, and see his splendid collection 

 of fossil corals. He accompanied me to the bed of the river, 

 where, although the water was not at its lowest, I saw a grand 

 display of what may be termed an ancient coral reef, formed by 

 zoophytes, which flourished in a sea of earlier date than the 

 carboniferous period. The ledges of horizontal limestone, over 

 which the water flows, belong to the old red sandstone, or De 

 vonian group, and the softer parts of the stone have decomposed 

 and wasted away, so that the harder calcareous corals stand out 

 in relief. Many branches of these zoophytes project from their 

 erect stems precisely as if they were living. Among other spe 

 cies I observed large masses, not less than five feet in diameter, 

 of Favosites gothlandica, with its beautiful honeycomb structure 

 well displayed, and, by the side of it, the Favistella, combining 

 a similar honeycombed form with the star of the Astrcea. There 

 was also the cup-shaped Cyathophyllum, and the delicate net 

 work of the Fcnestella, and that elegant and well-known Euro 

 pean species of fossil, called &quot;the chain coral,&quot; Catenipora cscha- 

 roides, with a profusion of others, which it would be tedious to 

 all but the geologist to enumerate. These coralline forms were 

 mingled with the joints, sterns, and occasionally the heads, of lily 

 encrinites. Although hundreds of fine specimens have been de 

 tached from these rocks, to enrich the museums of Europe and 

 America, another crop is constantly working its way out, under 

 the action of the stream, and of the sun and rain, in the warm 

 season when the channel is laid dry. The waters are now 

 twenty feet above their lowest, and more than forty feet below 

 their highest level, so that large spaces of bare rock are exposed 

 to view. 



On one of the window-sills of Dr. Clapp s library was displayed 



