146 Cincinnati Society of ITatural History. 



bedded la3^er near the base. Prof. Safford describes these rocks as 

 " abounding in Biyozoa." Maximum thickness 27 feet. The Central 

 Limestone — Thick-bedded, chert}- limestones, of a light-blue or dove- 

 color. This bed is the lowest exposure in the Central Basin of Ten- 

 nessee, and is described by Prof Saiford as about 100 feet in thickness. 

 Immediately above the Carter's Creek Limestone of this section, comes 

 the Orthis Bed of Prof. Safford, which is the lowest member of his 

 Nashville — Formation TV. The relations of this bed to the general 

 geological column are of such high interest, that I venture to examine 

 the subject of its fossil contents. 



Prof. Safford has furnished us a list of seventeen species* belonging 

 to this group, and including Brachiopoda, Gastropoda^ Lamellihran- 

 chiata, Cephalop)oda, and ChcBtetes. Of these but three are Hudson 

 River species exclusively. Of the remainder, five are Trenton or 

 Black river; seven are indifferently Trenton or Hudson river, 

 though generally described from Trenton localities; and one ranges to 

 the Chaz3^ The other two are species of Cypricardites from the Or- 

 this Bed. The conclusion to be drawn from this list of species is, 

 that the Orthis Bed, judged b}^ its paloeontological characters, is pre- 

 eminentl}^ Trenton, and is evidentl}^ more nearl}^ related to this forma- 

 than to the Hudson River. We may now resume the consideration of 

 the Kentucky river section. 



Beyond High Bridge the grade of the, road rises 176.1 feet in three 

 and one half miles, and this rise in the grade carries us entirely above 

 the heavy-bedded limestones at the river, to the same rugged and thin- 

 layered mass, which forms the upper part of the section, both here and 

 at Nicholasville. These rocks hold man}^ fossils that belong both 

 to the Trenton and Hudson River Groups, the most common of which 

 are Orthis testudinaria, Chcetetes lycoperdon, Zygospira modesta, 

 Raphistoma lenticulare of large size, and Mvrchisonia hellicincta. 

 With these fossils are found, however, a much larger number of tj^pical 

 Trenton species, as will be seen further on. These limestones con- 

 tinue to be the surface rock along the line of the railroad nearly to 



* The following is the list given by Prof. Safford: Monticidipora fihrom, Goldfuss, Hud- 

 son River; Strophoraena alternata, Conrad, Trenton and Hudson River; Orthis lyiuv, Eich- 

 wald, Trenton and Hudson River; 0. testudinaria, Dalman, Trenton and Hudson River; 0. 

 •^i^&o'gj^rt to, Conrad, Chazy to Trenton; Rhynchonella capax, Conrad, Hudson River; Zygos- 

 pira modesta , Say, Trenton and Hudson River; Ambonychia radiata, Hall, Trenton and 

 Hudson River; Cyrtodonta gantii, Safford, Orthis Bed; Cyrtodonta winclielii, Safford. Orthis 

 Bed; Jlodiolopsis modiolaris, Conrad, Hudson River; Murehisonia milleri. Hall, Trenton 

 and Hudson River; CyrtoUtes ornatus, Conrad, Hudson River; Bellerophon punctifrons, 

 Emmons, Trenton and Black River; Carinaropsis carinata. Hall, Trenton; Orthoceras per- 

 tinax, Billings, Black river; Endoceras rapax, Billings, Black River. 



