PLATE XLUI— Ck>nUnueil. 



Meeistella Haskinsi, Hiill. 



See Plate 44. 

 Figs. 23, 24. Dorsal and profile views of the usual form of the species. 

 Hamilton shales. Moscow, N. Y. 



Mekistella Bakkisi, Hall. 



See Plate 44. 

 Figs. 25, 26. Ventral and dorsal \'iew8 of different shells, giving the external characters. 

 Limestone of the Marcellus shales. Stafford, N. ¥. 



Mekistella rostkata, Hall. 



Figs. 27, 28. Dorsal and profile views, showing the usual form and size of the species. 

 TuUy limestone. Ovid, N. Y. 



Meeistella Meta, Hall. 



Figs. 29, 30. Dorsal and ventral views of an adult specimen. 

 Hamilton group. Delphi, N. Y. 



