Figs. 
PLATE LXXXIX. 
a — Spinifera. 
Leptodesma spinigerum. 
Page 177. 
* See Plate 21. 
1. A left valve preserving- the spiniform extension of the cardinal angle. 
Chemung group. Chemung river, above Elmira, N. Y. 
Leptodesma longispinum. 
See Plate 21. 
2, 3. Two left valves varying slightly in form and surface markings. 
4. A large imperfect right valve preserving a portion of the finely striated ligamental are; 
Chemung group.- Near Elmira, N. Y. 
Leptodesma Shumardi. 
Page 180. 
5, 6. Two left valves varying- somewhat in form and proportions. 
• Chemung group. Near Elmira, N. Y. 
Leptodesma potens. 
7. A nearly entire right valve of this species. 
Chemung group.. Near Olean, N. Y. 
Leptodesma robustum. 
Page 181. 
See Plate 21. 
8. A large left valve. 
Chemung group. Steuben Co., N Y. 
