THE DEVONIAN FISHES OF MISSOURI 69 



DEVONIAN STRATIGRAPHY 



Mr. R. R. Rowley has worked out the Devonian stratig- 

 raphy in Pike County.* At Louisiana it consists of four 

 feet of dark colored shales and is conformably overlain by the 

 Louisiana limestone of the Mississippian. Eight miles west of 

 Louisiana it has thickened to sixty feet or more of shales, and 

 a few miles to the southeast a limestone, called Hamilton by 

 Rowley, wedges in under the shales. 



Mr. D. K. Greger has kindly furnished the writer the 

 following section from near Fulton, Missouri: 



"The Devonian of Callaway County has a thickness of approximately 

 eighty feet and consists of dark, thin bedded, ironstained limestones at 

 the base becoming somewhat argillaceous upward and terminating in very 

 fine grained shales. Dr. Keyes has applied the name Callaway limestone 

 to the lower beds and the writer has named the upper part, which contains 

 no limestone and is separated from the lower by an unconformity, the 

 Craghead Creek shales. The Callaway limestone is best exposed on Rock 

 House branch south east of Fulton and consists of forty-two feet of thin 

 bedded limestone followed by nine feet of argillaceous concretionary 

 limestone containing pyrite crystals. Above the unconformity the Crag- 

 head Creek formation begins as dark blue or drab sandy shales with thin 

 calcareous partings becoming lighter in color upward and terminating 

 in soft yellow or gray siliceous shales. The thickness is approximately 

 twenty-five feet." 



The Craghead Creek shales contain Ptyctodus calceolus 

 teeth and so do the shales at Louisiana but the invertebrate 

 faunas are entirely distinct. Greger's list from the Craghead 

 Creek shales contains four corals, four crinoids, twenty-five 

 brachiopods without a Lingula, six pelecypods, two cephalo- 

 pods, and one bryozoan.f Lingulas make up most of the fauna 

 of the shales at Louisiana, a Stropheodonta has been reported, 

 and a few pelecypods occur. The Lingulas are abundant in 

 some horizons and some are very large. The question of the 

 correlation of these shales arises, but the data at hand are 

 insufficient for drawing conclusions. The Craghead Creek 



*Mo. Bu. Geol. Min., III. 2d series, pp. 24-26. 

 fAmer. Journ. Sci., XXVII, pp. 376, 377. 



