1 6 DAVENPORT ACADEMY OF NATURAL SCIENCES. 



was found in Cook's quarry just below the city, and which at his re- 

 quest was loaned to Professor Hall, who redescribed the species, illus- 

 trating both specimens in his great work on Palaeontology.* 



The next exposure westward was long known as the LeClaire quarry, 

 located within the city limits, but now entirely obliterated. For years 

 it had been visited, and collections made mainly from the Spirifer 

 Pennatus beds. The quarry had the appearance of being opened for 

 the sake of procuring .stone suitable for building purposes. Excava- 

 tion had gone down into the Phragmoceras beds, when the next suc- 

 ceeding limestones and shales must have become loosened, and resulted 

 in a confusion and commingling of rocks and fossils of both beds. 

 Here, as elsewhere, the Phragmoceras beds included their two most 

 marked divisions. The upper consisted of a series of thin, hard, 

 non-continuous la\ers of limestone. On the surface of many of these 

 were crowded the detached valves of Owen's Atrypa comis (the Gypi- 

 dula occidentalis of Hall), and corresponding so closely to Owen's 

 figure, particularly in the absence of frontal plications, that on men- 

 tioning the circumstance to Dr. Parry he responded that he had ac. 

 companied Dr. Owen to this very locality. Beneath these thin slabs 

 could be traced the other member stretching for eight or ten feet 

 down the bluff, a light grey, thick, heavy-bedded rock, in the rough- 

 ened face of which stood out the weathered forms of some of its most 

 ordinary fossils. 



As a third locality, we have the extension of these beds across the 

 river into Rock Island. One difference between this and other ex- 

 posures was that the series of upper thin layers was to some extent 

 absent. The upper member of the Phragmoceras beds graduated so 

 gently into the lower part of the Spirifer Pennatus beds as scarcely to 

 be recognized. Yet Professor Worthen did not fail at once to detect 

 the difference. 



In his description of the Devonian limestone between Rock Island 

 and Moline, he separated it on purely lithological grounds into three 

 divisions. The upper two correspond to Professor Calvin's Spirifer 

 Pennatus beds. The lower is the Phragmoceras, and cannot be better 

 described than in his own words: " These shaly limestones are under- 

 laid by a fine-grained grey or dove-colored limestoue, the up))er part 

 becoming tolerably massive." f 



* Natural History of New York. Paleeontology, Vol. VII., page 126, Plate xxiii., figures 

 16-18. 



t Geology of Illinois, Vol. I., page 121 ; Vol. V., page 223. 



