PLATE LXXXLX—Continued. 
Leptodesma Mortoni. 
Page 190. 
See Plate 21. 
Fig. 9. The specimen fig. 31, plate 21, redrawn to show the form of the body and size of the wing. 
Chemung group. Portville, Cattaraugus Co., N. Y. 
Fig. 10. The right valve fig. 32, plate 21, redrawn to show the proper form and characters of this valve. 
Chemung group. Portville, N. Y. 
Fig. 11. A cardinal view of a specimen, preserving the valves partially open and showing their comparative 
size. Chemung g-roup. Little Genesee, N. Y. 
Leptodesma Billingsi. 
Page 192. 
Fig. 12. A large left valve. 
Chemung group. Panama, N. Y. 
Fig. 13. A right valve agreeing in form and proportions with this species, but referred with some doubt 
on account of the geological position. 
Chemung group. Near Elmira, N. Y. 
Fig. 14. An imperfect left valve of somewhat different form. 
Chemung group. Panama, N. Y. 
Fig. 15. A small left valve from the same horizon as the specimen fig. 13. 
Leptodesma lepidum. 
Page 195. 
See Plate 21. 
Fig. 16. A left valve showing the form and surface markings. 
Chemung group. . Tioga Co., Pa. 
Leptodesma Agassizi. 
Page 182. 
Figs. 17, IS. Two left valves showing the characteristic form of this species. 
Fig. 19. A small right valve. 
Chemung group. Near Elmira, N. Y. . 
Leptodesma Stepiiani. 
Page 194. 
Fig. 20. A right valve. 
Figs. 21, 22. Two left valves showing the usual characters of the species. 
Chemung group. Bradford, Pa. 
Leptodesma disparile. 
Page 186. 
See Plate 25. 
Fig-. 23. A right valve showing the form and ornamentation. 
Fig. 24. A small left valve preserving the spiniform process. 
Chemung group. McKean Co., Pa. 
