PLATE LXVI. 



Sphenotus contractus. 



Page 399. 

 See Plate 94. 

 Fig. 1. A left valve jireserWng- the shell in part, and showing the antei-ioi muKculai- iuipres-sion. 



Cheraiing group. P/iUipxburf/h, N. Y. 

 Figs. 3, 4. Larger left valves. 



Chemung group. Philipsburgb, N. Y. 

 Fig. 5. A smaller left valve impei-fect at the posteiior extremity. 



Chemung group. Eight miles stmtli <if Mayville, N. Y. 

 Fig. 6. A small right valve somewhat compressed vertically, giving a narrow car<linal slope. 



Chemung group. Philipshurgh, N. Y. 

 Figs. 7-9. Right valves of .specimens showing gi'aJation in size and the muscular scais. 



Chemung group. Alleghany Co., IV. 1'. 

 Fig. 10. A right valve showing a wide post-cjirdinal slope and a rounded posteiior extremity, in which it 

 differs from the othei-s. . ■' A .0,-. 



Chemung grouj). RockinUe, N. T. -~' ~ 



Fig. 11. The inner side of the right valve fig. tJ oidarged, showing the ligamental area and a narrow gi-oove 



beneath the umbo. 

 Fig. 12. A right valve sho\ving anterior muscular impression. 



Chemung group. Near Oleati, N. Y. 

 Fig. 13. A left valve of elongate form. 



Chemung group. Near Olean, N. Y. 

 Fig. 15. A large left valve imperfect at the anterior end. 



Chemung group. Cattarauffu.t Co., N. Y. 

 Figs. 16, 17. Shorter forms which are referred to this species with doubt. 



Chemung group. Cattarattgus Cn., N. Y. 

 Fig. 19. A left valve doubtfully referi-eil to this species. 



Chemung group. Cherry creek, Cattaraugux Co., N. Y. 



SpHKNOTUS CLAVULU8. 



Puge 401. 

 Fig. 2. A small left valve. 



Chemung group. PhiUpxbiiryh, N. Y. 



Figs. 20-26. A series of valves showing the variety of size :ii](l form. 



Sphenotls kioii>u.s. 



Page 402. 

 Fig. 14. The i-ight siile of the original specimen. 



Burlington sandstone, liurliiujlan, Iirwa. 



^■•%. 



