The fossils classified below were collected from exposures or outcrops along that position of the creek just south of Oxford extending a distance of about a mile along the creek. This stretch was divided into four vertical levels.

The First or lowest level extended from a point on the lowest exposed ledge of limestone by a small juniper tree which is below a knotty wild cherry standing on top of the bluff a little more than one-fourth of a mile east of the railroad culvert, to a point five inches above the floor of the railroad culvert (marked at east end of the culvert). This level extended from 829 feet to 839 feet above the Gulf of Mexico.

The Second level extended from the point at the culvert, to a reddish brown glacial bowlder in the bed of the creek at the second bend of the creek west of the railrond (opposite a gneiss glacial bowlder on the left bank six feet higher up). This bowlder is about three hundred yards from the railroad. This level extended from 839 feet to 849 feet above the Gulf of Mexico.

The Third level extended from the above mentioned bowlder in the bed of the creek to a point in the bed of the creek about one hundred yards east of the iron Road Bridge over Collin's Run. This bridge is a little more than onehalf mile west of the railroad culvert. This level extended from 849 feet to 859

feet above the Gulf of Mexico.

The Fourth level extended from the upper limit of the third level to a point about one hundred yards above the confluence of three branches of Collin's Run which come together less than one hundred yards west of the iron Road Bridge. This level extended from 859 to 875 feet above the Gulf of Mexico.

These levels were all based upon a level of Miami University made by Dr. R. W. McFarland. There is no question about the accuracy of this level but it might be of interest to know how it was obtained. The low-water mark of the Ohio River at Cincinnati is 432 feet above the Gulf of Mexico. This was deter

mined by United States Government engineers many years ago. About 1867 or 1868 John W. Erwin, Canal Commissioner, who had charge of the Miami and Erie Canal, determined the difference in level of low-water mark of the Ohio at Cincinnati and the surface of the Miami and Erie Canal Basin in Hamilton, Ohio. Then Geo. T. Erhardt, Civil Engineer for the C., H. & D. Railroad, leveled from the surface of the Canal Basin to the C., H. & D. track in front of the depot at Hamilton. Mr. Campbell, Civil Engineer for the C., H. & D. Railroad, then furnished the difference in level between this point and a point in front of the C. H. & D. depot in Oxford. Dr. R. W. McFarland, who is a Civil Engineer of note, then leveled from this point up to the east door-sill of the Main Building of Miami University and found this to be 962 feet above the Gulf of Mexico. This door-sill was about six inches below the level of the present floor of the Main Building.

According to J. M. Nickles, of the United States Geological Survey, the stretch of creek from which these fossils have been collected is embraced in the Middle and Lower Richmond Groups of the Ordovician series.

I wish to thank Professor August F. Foerste of the Steele High School, of Dayton, Ohio, for his assistance in identifying the fossils.

Following is a list of the fossils collected from these levels, although it is, by no means, a complete list. They are classified in groups, and after each scientific name is the name of the person who first described the species. The Arabic numerals following the names indicate the levels in which the fossils were found. The letter "c" following any name indicates that that particular fossil is very

Strophomena nutans, James. 4.

Platystrophia (species intermediate between P. biforata and P. acutilirata). 4.

Ctenodonta (species resembling C. cingulata, Ulrich) 4.

OTIUM EST, SUPREMA LAETITIA

HORACE, BOOK II, ODE XVI.