54 Cincinnati Society of Natural History 



the same locality, possibly belonging to the same 

 species. All of the figures on this plate which are 

 numbered under 1 are from plaster casts prepared 

 by Dr. F. A. Bather of the British Museum, from 

 the original specimens. 



Fig. 2. Dinorthis carleyi insolens, Foerste. A, B, pedicel 

 valves. From base of Blanchester division of 

 Waynesville member of Richmond group, near 

 Miltonville, Ohio. 



Fig. 3. Dinorthis carleyi. Hall. A, B, pedicel valves; C, 

 brachial valve; D, E, interiors of pedicel valves. 

 Arnheim member of Richmond group, at Oregonia, 

 Ohio. 



PLATE III 



Fig. 1. Arctinurus harrisi. Miller. Pygidium of type, Liberty 

 member of Richmond group, Waynesville, Ohio. 



Fig. 2. Tripteroceras richmondensis, sp. nov. Transverse 

 section of specimen represented by figure 3 on 

 Plate I. 



Fig. 3. Hebertella Llandiloensis, sp. nov. 3, brachial valve 

 erroneously figured by Salter as belonging to Di- 

 northis retrorsa; a, posterior view of the same; 

 b, posterior view of same comliined with that of 

 Dinorthis retrorsa; e-h, outlines indicating curva- 

 ture from beak to anterior margin of specimens 

 bearing the same letter in figure 1 on plate II; 

 E-H, corresponding transverse sections across the 

 center of these valves. Bird's-hill, north of Llandilo, 

 in southern Wales. 



Fig. 4. Dinorthis retrorsa, Salter. Pedicel valves; 4, 4a, 

 exterior and cast of interior. The original of the 

 latter appears to have been lost, c, outline indicating 

 slope of hinge area and curvature of valve along the 

 middle line, from the beak to the anterior margin. 



