30 PROCEEDINGS OF THE NATIONAL MUSEUM vol.76 



position was not in accord with actual fact. The past decade has 

 witnessed a careful collection of detailed paleogeographical data, but 

 there has been no attempt to summarize these facts connectively. 

 A brief review of the knowledge of the Middle Devonian of the 

 northern Mississippi Basin has been sketched in a recent paper by 

 the author.^^ It was pointed out that the outcrops of Devonian 

 rocks nearest adjacent the Traverse on the west, those of eastern 

 Wisconsin, were deposited at a considerably later time; and that 

 the Cedar Valley formation, the Devonian of Iowa bearing closest 

 faunal connection with the Milwaukee beds, lies above the " Cuboides 

 zone " in that State, placing it unquestionably in the Upper 

 Devonian. 



EVIDENCES FOR PROPER POSITION IN THE GENERAL TIME SCALE 



Beds of Traverse age again appear at the surface in northwestern 

 Ohio. These outcrops trend in a general northeast-southwest direc- 

 tion from Lucas to Paulding Counties and have been described in 

 two bulletins of the Geological Survey of Ohio.^^ The Traverse 

 with a slight northwest dip here appears on the surface as the south- 

 eastern portion of its broadly concentric outcrop and overlaps to 

 the eastward on the Cincinnati axis. The actual thinning and dis- 

 appearance of these beds has not been traced, but shortly to the 

 eastward the same stratigraphic position is held by the eastwardly 

 thickening Delaware limestone and its distinctive southern fauna. 

 The greatest thiclniess of Traverse beds in this region is seen at 

 Ten Mile Creek, a little south of Silica and 10 miles west of Toledo 

 in Lucas County, where the exijosed section shows some 47 feet of 

 Traverse delimited below at the contact with the Columbus lime- 

 stone carrying a true Onondaga fauna. The Traverse apparently 

 thickens westward, but that the complete thickness is in the neighbor- 

 hood of 50 feet at its westernmost exposure may be seen in the close 

 proximity of the Ohio shale to the west. 



The Traverse beds exposed in northwestern Ohio bear a fauna 

 identical with that found in the lower part of the Presque Isle stage 

 farther northward in the vicinity of Alpena in Michigan. Follow- 

 ing is a partial list of species common to the Traverse of Ohio and 

 the Bell shale of Michigan. 



Heterophrentis prolifica (Billings). 

 Prismatophyllum cf. davidsoni (Edwards and Haime). 

 Ceratopora near jacksoni Grabau. 

 Cystodictya near gilberti (Meek). 



^ Pohl, E. R. Middle Devonian Pelecypods of Wisconsin and Their Bearing on Corre- 

 lation. Wash. Acad. Sci., vol. 19, No. 3, pp. 53-59, 1929. 



^ Stauffer, C. L. Geol. Surv. Ohio, ser. 4, Bull. 10, pp. 144-156, 1909. Stewart, G. A. 

 Geol, Surv. Ohio, ser. 4, Bull. 32, 1927. 



