I02 STUART WELLER 



Illinois and Indiana, as well as in a basal Kinderhook shale in Missouri. 

 At the base of the formation a thin band occurs which is frequently 

 crowded with the teeth of Ptyctodus calceolus, the same species which 

 is present in the State Quarry beds and one which also has a wide 

 distribution at the very base of the Kinderhook formations. 



Following the Devonian of the Interior Continental Province to 

 the northwest, it is next well exposed in Manitoba, and has been well 

 described by Tyrrell. ' Approximately 5 10 feet of strata are recognized, 

 the lower 100 feet not having afforded any fauna. The beds referred 

 to the Middle Devonian (Winnipegosan) are characterized by the 

 presence of Gypidula comis throughout, and by Strmgocephalus 

 biirtoni in the upper portion. The last of these species does not occur 

 in Iowa, but Gypidula comis is an abundant and characteristic member 

 of the fauna of the upper beds of the Wapsipinicon stage, where it is 

 associated with Rhynchonella intermedia Barris {Hypothyris cuhoides) . 

 In western Europe Stringocephalus hurtoni is the index fossil of the 

 Stringocephalus limestone at the summit of the Middle Devonian, and 

 occurs immediately beneath the Cuboides zone. The Devonian beds 

 superjacent to the Stringocephalus beds in Manitoba have been 

 referred to the Upper Devonian by the Canadian geologists, a cor- 

 relation which is doubtless correct, since the faunal succession is 

 similar to that in Europe, where Stringocephalus hurtoni marks a 

 distinct horizon at the summit of the Middle Devonian. 



The Devonian fauna of the Mackenzie basin has been described 

 by Whiteaves^ and has been correlated with the Cuboides zone of 

 Europe and New York, a correlation which seems to be based on 

 substantial evidence. Seventy-six forms are specifically identified, 

 twenty-nine of which are either present or are represented by close 

 relatives in the European faunas of similar age, while twenty-two are 

 identified with American Hamilton species, ten with lowan and seven 

 with Chemung forms. In the Mackenzie basin the Stringocephalus 

 zone has not been so clearly recognized as in Manitoba, although it is 

 indicated in at least one locality. The entire Devonian section in the 

 Mackenzie Basin consists of 2,800 feet of strata, but a considerable 

 part of the lower portion may be of greater age, and the entire fauna is 



1 Geol. Siirv. Canada, Ann. Rep. V (N. S.), Pt. I, pp. 204-9 E. 



2 Cont. Can. Pal., I, 197-253, pis. 27-32. 



