PLATE XVI— Continued. 



Genus CHONETES, Fischer he Waldheim. 



Page 303. 



Chonetes Verneuiliana, Norwood and Pratteii. 

 Figs. 20, 21. Two views ; showing the strong median consti-iction. X 2. 

 Coal Measures. Illinois. 



Chonetes mesoloba, Norwood tiiid Pratteu. 

 Fig. 22. A pedicle-valve ; showing the median fold. X 2. 

 Coal Measures. Illinois. 



Chonetes concentrica, de Koaiuck. 



Fig. 23. A species in which the surface is covered with strong concentric wrinkles. This species may not 

 prove congeneric with Chonetes striatella, Dalman. 



Lower Carboniferous limestone. Vise, Belgium. 



Chonetes Logani, Norwood and Pratteu. 

 Fig. 25. The interior of a brachial valve ; showing the brachial ridges. Drawn fi-om a gutta-percha im- 

 pression. X 2. 



Waverly group. Wayne county, Ohio. 

 See Part ii, Volume VIII, for further illustration. 



Chonetes deflecta, Hall. 



Fig. 28. The interior of a brachial valve. X 2. 



Hamilton group. Western Nene York. 



Chonetes lineata, Courad. 



Fig. 34. The interior of a pedicle-valve ; showing the ai-ea, teeth and muscular impressions. X 2. 

 Corniferous limestone. Western New York. 



Chonetes syrtalis, Conrad ( = 0. coronala, Conrad). 

 Fig. 39. An internal cast of the brachial valve ; showing the brachial ridges. 

 Fig. 41. An internal cast of the pedicle- valve. 

 Fig. 43. An impression of the exterior of a large shell. 



Hamilton group. Eastern New Ymk. 



Genus STROPHEODONTA, Hall. 



(See Plates XIII, XIV, XV, XVb, XX.) 

 Page JSl. 



Stropheodonta callosa, Hall. 



Fig. 37. An enlarged cardinal view of the pedicle- valve ; showing the muscular impressions and crenula- 

 tions of the ai'ea. 



Schoharie grit. Near Clarksville, N. Y. 



