380 The Ohio Journal of Science [Vol. XIX, No. 7, 



their higher fold and deeper sinus. They may, however, be 

 merely variations of the species identified above from the same 

 locality as Camarotoechia indimiensis. 



Rhynchotreta cuneata americana Hall. 



Plate XVI, Figs. .3 A, B; Plate XVII, Fig. 3. 



In typical Rhynchotreta americana, from the Waldron shales of 

 Indiana, the two median plications on the fold of the brachial valve are 

 wider and more conspicuously elevated than the two lateral plications 

 on this fold; moreover, the anterior part of the shell is widened laterally 

 so strongly that the postero-lateral outline becomes distinctly concave 

 in mature individuals. 



At the Whitfieldella horizon, nine feet above the base of the Lower 

 or Bisher member of the West Union fonnation, in the eastern part of 

 Hillsboro, Ohio, the two lateral plications on the median fold of Rhyn- 

 chotreta cuneata americana (Plate XVI, Figs. 3, A, B), are only moder- 

 ately below the two median plications on this fold and all four plications 

 are of about the same width; moreover, the rate of widening of the shell 

 anteriorly is more even, so that the postero-lateral margins are nearly 

 straight. However, in specimens obtained from about the same 

 horizon, at West Union, Ohio, the two median plications on the fold of 

 the brachial valve are conspicuously elevated above the two lateral 

 plications on this fold, as in typical Rhynchotreta cuneata americana, so 

 that it does not seem possible to distinguish the forms from the Lower 

 part of the West Union formation from the typical forms in the Waldron 

 shale unless it be assumed that two forms are present in the West Union 

 bed, an assumption which appears premature in our present meager 

 information regarding the range of variation among the specimens 

 occurring in the West Union formation. 



Rhynchotreta cuneata americana is abundant at some localities 

 in the upper part of the West Union formation, associated with 

 numerous specimens of a small-celled species of Favosites. 

 The specimen here figured (Plate XVII, Fig. 3), was obtained 

 in the upper part of the exposures in the road-cut, south of 

 Carr's station, in Lewis county, Kentucky. It presents a cast 

 of the interior of the brachial valve, with its median septum, also 

 a cast of the deltidial cavity. 



Atrypa reticularis elongata, var. nov. 

 Plate XVI, Figs. 4 A-C. 



In his report on Greene County, in the second volume of 

 the Geology of Ohio, published in 1874, on page 671, Prof. 

 Edward Orton stated regarding the West Union Cliff rock: 

 ''It is to be identified principally by its containing a fossil 



