Bedford shale 



GIRTY, GEOLOGIC AGE OF THE BEDFORD SHALE 313 



least represents a conspicuously different faunal development, the ques- 

 tion becomes more confusing and the conclusion somewhat less satis- 

 factory. 



A search among the American faunas now known for one which is 

 comparable with that of the Bedford shale probably reveals none so simi- 

 lar in a general way as a certain phase of the Kinderhook developed at 

 Hamburg, Illinois, and the closely related one developed in the Glen 

 Park limestone member of the Kinderhook of Missouri. The constitu- 

 tion of these faunas, generically considered, is surprisingly close and 

 many of the species seem to be related. These may be arranged in 

 parallel columns, as follows : 



Limestones of the Kinderhook at Glen 

 Park, Louisiana or Hamburg 

 Schuchertella herricki Schuchertella chemungensis 



Productella pyxidata var. tedfordensis Productella pyxidata 

 Rhipidomella n. sp. Rhipidomella missouriensis 



Cryptonella ? sp. Cryptonella sp. 



Delthyris n. sp. Delthyris missouriensis 



Syringothyris carteri Syringothyris carteri 



Spirifer aff. marionensis ? Spirit er marionensis 



Athyris aff. hannioalensis Athyris hannioalensis 



Macrodon hamiltonice Macrodon sulcatus 



Leda diver sa Leda diversoides 



Bellerophon aff. jeffersonensis Bellerophon jeffersonensis 



Platyceras sp. Platyceras erectoides 



Tropidodiscus cyrtolites ? Tropidodiscus cyrtolites 



There is also a Chonetes in both faunas, though of not very close rela- 

 tionship; a Camarotcechia, though the Bedford form is large and the 

 Hamburg form small; and a Nucleospira, though also specifically dis- 

 tinct. In fact, while many of the same genera are present in both areas, 

 there are very few species which are really identical, and those for the 

 most part belong to genera in which the identification of species is diffi- 

 cult and a satisfactory identification impossible. Syringothyris carteri 

 is an example. 



Professor Weller 17 has pointed out the close relationship which exists 

 between the Kinderhook fauna at Glen Park, Missouri, and that from 

 the oolitic beds at Hamburg, Illinois, and he has also called attention to 

 the conspicuous Devonian fades which these faunas present (p. 463), a 

 resemblance which (like that of the Bedford) would seem to ally them 

 with the Hamilton rather than with the later Devonian faunas. Pro- 

 fessor Weller finds that 12 out of the 31 species at present known from 



1T Acad. Sci. St. Louis, Trans., vol. 16, p. 462 et seq. 1906. 



