132 Cincinnati Society of Natural History 



of Plafystrophia colbiensis are given in the Denison University 

 Bulletin, vol. XVI, plate IV. Orthorhynchula linneyi is figured 

 on plate III. 



17 — Eridorthis — Eridorthis nicklesi, Foerste (Plate I, Figs. 

 5A, B, €), was identified at 60.3, 59.1, 54.5, and 54.3 miles from 

 Ludlow. Eridorthis rogersensis was identified from 60.3, 59.7, 

 59.5, 59.1, 55.3, 54.5, 54.3, and 54.2, but is the less common form. 

 One of these two species of Eridorthis, but not further identified, is 

 present also at 58.8, 58.7, and 54.8. The occurrence of this form 

 at Riverside, north of Ford, and along the Ohio river at Brent, 

 Nine-mile creek, and Ivor has already been noted. It occurs 

 also near Hutchison station, on the railroad from Lexington to 

 Winchester. ' 



18 — Clitambonites rogersensis, Foerste (Plate II, Figs. 6 A, 

 B, C, D) — This species occurs at the railroad cut south of Rogers 

 Gap, and also northwards at the cuts 59.1, 55.3, 54.8, and 54.3 

 miles from Ludlow. It is found also at Riverside, the station one 

 mile north of Ford, at the same stratigraphic horizon. No species 

 of Clitambonites is known from the Eden or Maysville, of the areas 

 at or surrounding Cincinnati. 



19 — Zygospira reciirvirostra, Hall (Plate I, Fig. 2) — This 

 species is distinguished from Zygospira modesta by the broad, 

 shallow median depression of the brachial valve, within which 

 the radiating plications are subequal in size, while in typical Zygo- 

 spira modesta the median depression of the brachial valve tends 

 to be deeper, the radiating plications tend to be more angular, and 

 the middle plication within the median depression usually is dis- 

 tinctly and even conspicuously larger than those at either side. 

 Moreover, in Zygospira modesta, the median elevation of the ped- 

 icel valve tends to be slightly more evident, and the median groove 

 along this elevation to be slightly more conspicuous. The speci- 

 mens of Zygospira recurvirostra here figured were obtained at 

 the railroad cut 65, one mile north of the station at Cynthiana. 

 Similar forms occur at many localities between Rogers Gap and 

 Sadieville, and at numerous localities elsewhere in the Trenton. 

 The types were obtained in the Trenton of New York. 



28 



