WITH THOSE OF NEW YORK. 283 



layers the rock becomes coarser grained or semi-crystalline, and 

 contains numerous fossils of the genera Delthyris, Atri/pa, and 

 large numbers of the Pentremites. The most remarkable fossil of 

 this portion of the rock, and which occm*s just above the fossils 

 named, is the Archimedes of Lesueur, a singular coral, appearing 

 as an expansion somewhat like the Retepora twisted spually 

 round an axis ; or rather, the edge of the coral, by thickening and 

 folding, forms the axis. This curious fossil always holds the 

 same position in the rock, the character of which differs from 

 that above or below, being often ferruginous or yellowish in color 

 and fine-grained. This portion of the rock contains, besides the 

 Archimedes, one or two other corals, and one or more species of 

 crinoidea. 



This portion is succeeded by a beautiful light-colored oolitic 

 mass, containing numerous fragments of fossils, the principal of 

 w^iicli were Producti, some perfect specimens being obtained. 

 A TrilobUe, a portion of the head of which resembles an Asa- 

 phifs, also occurs in this part of the rock. It is a very persistent 

 mass, being seen at numerous and distant points. Its character 

 as an Oolite, is as perfect as specimens from Bath, in England, 

 and its chalky and fissile nature, considered alone, would almost 

 induce one to regard it as a more recent formation. Its position, 

 however, cannot be mistaken, for, about one mile below Leav- 

 enworth, it is. seen passing beneath the gray sandstone before 

 mentioned. At this point, without any intermixture of the two 

 deposits, we pass from a pure oolitic limestone to an equally 

 well-characterized quartzose sandstone. 



This limestone was again examined near the mouth of Oil 

 Creek, la., where it presented the same essential characters as 

 described, and the same order of the parts. Opposite the mouth 

 of Little Blue river, on the Kentucky side, the junction of the lime- 

 stone and conglomerate presents a singular siliceous aggregate, 

 containing abundance of shells, and having somewhat the char- 

 acter of Buhrstone. From this place to the Wabash, there was 

 httle of interest to be seen ; the rocks approaching the shore in 

 many places, indicated along the whole distance the existence of 

 the great coal formation of the Illinois or Wabash basin. From 

 the section it will be perceived that the Wabash flows in the 



