[•I. \Ti, \\l i iintin ii . 



LEFT! PDESMA POTENS. 

 Page 188 

 See Plates '-••-' and 89. 

 21: A right valve referred to this species. 



Chemung group. Conewaugo, Cattaraugus Co., X. Y. 

 i 30. A left valve showing the form and proportions of the shell. 



Chemung group. Portville, Cattaraugus Co., X. Y. 



Leptodesma PROTEXTUM. 

 Page i- 1 

 Figs. 22, 23. A left and a right valve in the same association. 



Chemung group. Chemung fiver. Ujiper Narrows, X. Y. 



L/EPTODESMA SOCIALE. 



Page 187. 

 Figs. J4, 25. Two left valves showing the form of the shell and surface ornamentation, x 2, from Eg. 27. 



Chemung group. Conewango, Cattaraugus Co., X. Y. 

 Fig. 26. An enlarged view of a right valve from the same Hock. 



Fig. 27. A frag nl of stone with several valves of this species, natural sizo. 



I'ii:-. 28. An impression of a left valve, retaining a pari of tin- right valve in place. 

 Chemung group. Conewango, Cattaraugus Co., X. Y. 



!•':-. :;:!. A Frag a I of rock with a right and a lef I valve showing their comparative form. 



Chemung group. Broom* Co., X. Y. 

 Fig. 34. A right valve nl' larger suse and broader form, associated with tig. 33. The extremity of the wing 

 should be produced farther than is represented. This and the preceding figure are referred 

 to this species with some doubt. 



Leptodesma Morton!. 



Page I 1 '" 

 See Plate 89. 

 Pigs. 29, 31. Two left \ .• i K • ■ > varying somewhat in size .-11111 proportions. 

 Pig. :!'.'. A right valve. This specimen is redrawn on plate 89, Sg. 10. 

 Chemung group. Portville, Cattaraugus Co., X. Y. 



Leptodesma Lichas. 



Page 282 



See Plate 91. 

 Pigs. 35 37. Three left valves. 

 Pig 38. A large left valve of this species. The cardinal extremities should be produced in the figure to 



correspond with fig. 87. 

 Pig. 39. A small right valve. 



Chemung group. rg, Alleghany Co., X. Y. 



Leptodesma LEPIDUM. 

 Page 195 



See Plate 89. 

 Fig. 10, A left valve, as soon lying in the rock, ami with a parr of the right valve in place. The concavity 



of 1 ho margin of the wing i- repi-esented a- 1 leep. 



Chemung group. Philipsbtirg, X. Y. 



