DEVONIAN AND MISSISSIPPIAN FAUNAS lOl 



these lowan beds, it seems safe to conclude that these higher Wapsi- 

 pinicon beds are essentially equivalent in time with the Tully limestone 

 of New York. Furthermore, almost the only fossil species in the 

 lower Wapsipinicon beds is Martinia subumbona, which also is a 

 common Tully limestone species. 



Another point of contact between the faunas of the lowan and the 

 New York provinces is found in the faunas of the Lime Creek shales 

 of Iowa and the High Point sandstone near Naples, N. Y. The High 

 Point bed lies at the extreme top of the Portage in the New York 

 section, and in a total fauna of 26 species, 14 are also present in the 

 Lime Creek beds of Iowa.' This large proportion of identical species 

 may be considered as a sufficient basis for the essential correlation of 

 the beds. 



If these two correlations are correct, a basis is established for the 

 correlation of the entire Devonian series of Iowa, the Wapsipinicon 

 being, in the main, the time equivalent of the later Hamilton of the 

 New York section, its termination being essentially contemporaneous 

 with the Tully limestone, the Cedar Valley being contemporaneous 

 with the Portage group of New York, and the Lime Creek being 

 contemporaneous with the closing stages of the Portage and the open- 

 ing of the Chemung. There is no evidence whatever of the presence 

 of any beds of Onondaga age in Iowa. 



The invertebrate faunas of the so-called Upper Devonian forma- 

 tions of Iowa are less prolific than those of the Cedar Valley beds. 

 The Lime Creek fauna includes a number of forms which are recurrent 

 from the Independence shales near the base of the Wapsipinicon, a 

 distribution which suggests the unity of the entire Devonian fauna of 

 Iowa, and, further, that the Lime Creek is not far removed from the 

 subjacent beds although there is apparently an unconformity between 

 them. The State Quarry beds contain a number of distinctly Devon- 

 ian brachiopods, among which may be mentioned Pugnax alta which 

 also occurs in the Lime Creek shales, but the most conspicuous 

 feature consists of the fish remains, Ptyctodiis calceolus being the most 

 abundant form. In the Sweetland Creek shales invertebrates are few 

 in number, a species of Spathiocaris being perhaps the most common, 

 a species which also occurs in the New Albany black shale of southern 



1 Clarke, Bull. U. S. G. S., No. i6, p. 75. 



