PLATE LV 



PAGR 



Figs. 1-4. LEPIDOCOLEUS JAMESI (Hall and Whitfleld) 371 



1. Sketch showing the plates in position. 



2, 3. Detached plates enlarged. 



Ordovician (Cincinnatian), Eden shale, Cincinnati, Ohio. 



4. A broader plate referred to this species. X 10. 



Ordovician (Mohawkian), Trenton Is., Trenton Falls, New 

 York. 



Figs. 5, 6. LOPHOSPIRA (RUEDEMANNIA) LIRATA Ulrich 295 



5. A specimen with numerous spiral ridges on the basal part of the 



volutions. 



6. Portion of the lower part of the last whorl of same including the 



band. X 3. 



Ordovician (Cincinnatian), Eden shale, Newport, Kentucky. 



Figs. 7, 8. HORMOTOMA GRACILIS (Hall) 292 



View natural size, and a portion enlarged, of the typical form of this 

 species. 



Richmond (Maquoketa) shale, Graf, Iowa. 



Figs. 9-11. SINUITES GRANISTRIATUS (Ulrich) 314 



9. Lateral view of a specimen. 



10. Dorsal view of an average example. 



11. Apertural view showing form of mouth and extent of the gran- 



ostriate expansion. 

 Ordovician (Cincinnatian), Eden shale, Covington, Kentucky. 



Figs. 12-21. SINUITES CANCELLATUS (Hall) 313 



12, 13. Two views of a cast of the interior showing strong wrinkles of 



growth near the aperture. 



14. Apertural view of shell with mouth less expanded than usual. 

 15. 16. Two views of a small cast. 



Ordovician (Mohawkian), Black River and Trenton forma- 

 tions of Minnesota. 



17. Dorsal view of a globose variety. 



18. Surface of left lobe of outer lip. X 4.5. 



Ordovician (Cincinnatian), Eden shale, Covington, Kentucky. 

 19-21. Three views of an average entire shell. 



Ordovician (Mohawkian), Trenton shales, Chatfleld, Minne- 

 sota. 



Figs. 22-24. TETRANOTA OBSOLETA Ulrich 310 



Three views of the type. 



Ordovician (Mohawkian), Trenton shale, Goodhue County, 

 Minnesota. 



Figs. 25, 26. LIOSPIRA MICULA (Hall) 296 



Two views of a nearly perfect example. 



Ordovician (Cincinnatian), Eden shale, Covington, Kentucky. 



Fig. 27. ORTHOCERAS TRANSVERSUM Miller 324 



Type specimen, showing the transverse surface markings. 



Ordovician (Cincinnatian), Eden shale, Cincinnati, Ohio. 



Figs. 28-31. BYTHOCPRIS CYLINDRICA (Hall) 371 



28, 30, 31. Views of a complete carapace. X 20. 



29. Interior of a right valve. X 20. 



Ordovician (Cincinnatian), Eden shale, Cincinnati, Ohio. 



Fig. 32. ULRICHIA BIVERTEX (Ulrich) 370 



Right valve showing the two prominent nodes. X 20. 



Ordovician (Mohawkian), Trenton shales, Montgomery 

 County, New York. 



Fig. 33. APARCHITES MINUTISSIMUS (Hall) 366 



Valve highly magnified. 



Ordovician (-Cincinnatian), Eden shale, Cincinnati, Ohio. 



Fig. 34. CERATOPSIS CHAMBERSI (Miller) 369 



Valve illustrating the prominent spine. Highly magnified. 



Ordovician (Cincinnatian), Eden shale, Cincinnati, Ohio. 

 Figs. 1-3, 33, 34, are after Hall and Whitfield; 6, 32 after 

 Ruedemann; 4-26 after Ulrich and Scofield; 27 after Miller; and 

 28-31 after Ulrich. 



405 



