PLATE LXYI. 
Sphenotus contractus. 
Page 399. 
See Plate 94. 
Fig - . 1. A left valve preserving the shell in part, and showing the anterioi muscular impression. 
Chemung group. Philipsbiirgh, N. Y. 
Fig's. 3, 4. Larger left valves. 
Chemung group. Philipsburgh, N. Y. 
Fig - . 5. A smaller left valve imperfect at the posterior extremity. 
Chemung group. Eight miles south of Ma.yville, N. Y. 
Fig. 6. A small right valve somewhat compressed vertically, giving a narrow cardinal slope. 
Chemung group. Philrpsbicrgh, N. Y. 
Figs. 7-9. Right valves of specimens showing gradation in size and the muscular scars. 
Chemung group. Alleghany Co., N. Y. 
Fig. 10. A right valve showing a wide post-cardinal slope and a rounded posterior extremity, in which it 
differs from the others. 
Chemung - group. Rockville, N. Y. 
Fig - . 11. The inner side of the rig-ht valve fig - . 6 enlarged, showing the ligamental area and a narrow groove 
beneath the umbo. 
Fig - . 12. A light valve showing anterior muscular impression. 
Chemung - group. Near Olean, 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. Cattaraugus Co., N. Y. 
Figs. 16, 17. Shorter forms which are referred to this species with doubt. 
Chemung group. Cattarav,gus Co., N. Y. 
Fig. 19. A left valve doubtfully referred to this species. 
Chemung g - roup. Cherry creek, Cattaraugus Co., N. Y. 
Sphenotus clavulus. 
Page 401. 
Fig. 2. A small left valve. 
Chemung group. Philipsburgh, N. Y. 
Figs. 20-26. A series of valves showing the variety of size and form. 
Fig. 
Sphenotus rigidus. 
Page 402. 
14. The right side of the original specimen. 
Burlington sandstone. Burlington, Iowa. 
