PLATE LXXIV. 



MiCRODON (Cil'UlCAKDKI.l.A) UKEOAUIUS. 

 Page 309. 

 See Plate 73. 

 Figs. 1, 2. Right and left valves. 



Chemung group. Cortiand, N. Y. 

 Fig. 3. A left valve of more elongate form. 



Fig. 4. A small left valve enlarged to two diameters. The striie are represented as too regular and tliu 

 beak too elevated. 



Chemung gi-oup. Near Elmira, N. ¥. 



MiCRODON (Cypricardella) bellistriatus. 



Pago 308. 

 See Plates 42, 73. 

 Figs. B, 6. Two right valves of elongate form. 



Chemung group. Near Elmira, N. T. 

 Figs. 7, 8. Right and left valves. 



Lower Chemung group. Ithaca, N. Y. 

 Fig. 9. The hinge of a left valve showing cai'dinal teeth and ligamental area, enlarged. 



Hamilton group. Slu>re of Skaiieatdes lake, N. Y. 

 Fig. 10. The hinge of a right valve, showing similar characters, enlarged. 



MiCRODON (CyPRICARDELLA) RE8ERVATCS. 

 Piigc 313. 

 Figs. 11-13. Three valves showing the principal characters of this species. 

 Waverly group. Licking Co., Ohio. 



MiCRODON (CyPRICARDELLA) COMPLANATU8. 

 Page 3U. 

 See Plate 42. 

 Figs. 14-18. A series of valves showing the piincipal variations in size and form of this species. 



Hamilton gi-ouj). Schoharie Co., N. Y. 

 Fig. 19. The interior of a right valve, as obtained from a gutta-percha impression in a natural mould, 

 showing hinge characters, anterior muscular scars and pallial line. 



MiCRODON (Cypricardella) TENUISTRIATUS. % 



Page 310. 

 See Plates 42, 73. 

 Figs. 21, 22. The hinges of a left and a right valve showing cardinal teeth and ligamental area, enlarged to 

 two diameters. 



