GUELPH FAUNA IN THE STATE OF NEW YORK I 23 



similarity of lithological character there seemed no sufficient ground for 

 separating them from the nonfossiliferous bed of the Onondaga salt 

 group. Since, however, in Canada these beds attain considerable impor- 

 tance, and (admitting the conclusions above given) acquire a still greater 

 thickness and more distinctive character on the Mississippi river, it seems 

 necessary to elevate these to the same rank as the other groups of the 

 series. 



Hall here first clearly recognizes the Gait beds as a separate group and 



this position was strongly reiterated in Paleontology of New York, 1859, 



3:30. 



This correlation of the Le Claire limestone was soon after attacked by 

 A. H. Worthen x who claimed that the limestone was without any true 

 lines of bedding, that Hall greatly overestimated its thickness 2 and that the 

 beds and fossils at Le Claire were to be correlated with those of Bridgeport 

 near Chicago and Port Byron 111., " all of which are claimed to represent 

 but the Niagara limestone." It would appear, however from Worthen's 

 statements that the fossils upon which he bases his views, specially Penta- 

 merus oblongus, occur only in the lower part of the bed at Bridge- 

 port and Port Byron, while Hall already cited a distinct Guelph form in 

 Pentamerus occidentalis from the Le Claire limestone. Hall and 

 Clarke have cited several species of Trimerella and Monomerella from Port 

 Byron and other localities of this dolomite and there can be no doubt that 

 the Guelph is represented therein. 



This rock is described by Worthen 3 as follows : 



At Bridgeport, near Chicago, the rock presents the same general char- 

 acters as at Port Byron and Le Claire, and is extensively used for the manu- 

 facture of lime. West and northwest of Chicago and just outside the city 

 limits, it is highly charged with petroleum. . . This bituminous portion of 

 the limestone is from 35 to 40 feet thick, and at the artesian well was found 

 to be underlaid by about 80 feet of regularly bedded limestone, which no 

 doubt includes the Athens marble and the Joliet limestone. 



1 Am. Jour. Science. 1862. 33:46-47; Geol. Sur. Illinois. 1866. 1:30. 



2 The latter point was conceded by Hall in the N. Y. State Cab. Nat. Hist. 20th An. 

 Rep't. 1867. p. 307. 



3 Geol. Sur. Illinois. 1866. 1:132. 



