Geology and Natural History. 467 



it of faunas representing two distinct and successive epochs of 

 the Niagara group." The earlier of these faunas is "correlated 

 with that of the Lockport limestone of New York. The later 

 fauna which has been recognized contains many species of the 

 Guelph limestone fauna of Canada, which has not hitherto been 

 known to occur in Indiana." The lower beds are called the 

 "Noblesville dolomite" because no trace of the Guelph fauna 

 appears in it. 



The higher formation is named the Huntington. " The bulk of 

 this fauna consists of a congeries of cephalopod and gasteropod 

 species, mostty of large size, together with a few heavy-shelled 

 brachiopods. Only four of the fifty species of brachiopods which 

 occur in the Noblesville rocks of northern Indiana have been 

 recognized in the collections from Huntington." 



Discussion by the Reviewer. — As stated by Kindle, the Nia- 

 garan deposits of northern Indiana include two well-marked hori- 

 zons equivalent to the Lockport and Guelph formations of New 

 York. Clarke has recently shown that the Lockport limestone 

 has in its upper portion a true Guelph fauna ; hence it may be 

 said that in a general way the Noblesville and Huntington for- 

 mations are equivalent to the Lockport and probably all of the 

 Lockport of New York and the Guelph of Ontario. The Nobles- 

 ville fauna is in the main made up of brachiopods, while the 

 Huntington is essentially a gasteropod and cephalopod fauna. 



Another important fact is indicated but not stated by Kindle. 

 This is the absence of the Waterlime horizon in northern Indiana, 

 although it is present over a great length of the state of Ohio. 

 It is true that Waterlime is reported about Kokomo, Indiana, but 

 the eurypterids from here are, with one exception, not those of the 

 Waterlime, either of New York or Ohio. Further, Conehidium 

 colletti of Kokomo is of the generic type abundant in the Nobles- 

 ville, and in no other American place is this genus known above 

 the Guelph. The occurrence here also of a Wilsonia ( W. koko- 

 moensis) is further suggestive of Noblesville. The conclusion 

 seems warranted that the Kokomo cement beds are probably of 

 Noblesville age rather than of the Huntington and especialty the 

 Waterlime or Bertie of New York. This conclusion finds further 

 support in the fact that nowhere south of northern Indiana along 

 the western side of the Cincinnati geanticline are known strata 

 having a Guelph fauna. The work of Foerste in southern Indiana, 

 Kentucky, and Tennessee indicates that the Silurian closed with 

 beds not younger than the Lockport. All of Indiana was land 

 from the close of the Guelph to the beginning of Onondaga time. 

 In other words, during this time there was deposited in eastern 

 New York all of the Cayugan, Helderbergian, and Oriskanian — 

 a time of consideration duration. The first succeeding subsidence 

 began in the south (Tennessee), for the Silurian is overlain by 

 Helderbergian rocks of New Scotland age. In the north, subsi- 

 dence did not take place until just before Onondaga time, since 

 the oldest Devonian strata are of latest Oriskanian age (Decew- 



Am. Jour. Sci. — Fourth Series, Vol. XVIII, No. 108. — December, 1904. 

 32 



