PLATE XLVIU— Continnoil. 



Pal^oneilo oonsthicta, var. flexuosa. 



PageSU. 

 Figs. 17-30. A aeries of specimens illustrating- this variety of form. 

 Lower Chemung gi-oup. Nvar Ithma, N. V. 



Pal.*;oneilo plana. 



Figs. 21-23. Three valves preserving the surface markings on the body of the shell and showing the crenu- 



lations of the hinge, enlarged. 

 Fig. 34. A cast of the interior showing the crenulations of the hinge, enlarged. 



Hamilton group. Tinker's falls, Orunidaga Co., A'. Y. 

 Fig. 25. A cast of the interior of a left valve preserving muscular imprints and hinge crenulations, enlarged. 



Hamilton group. Butternuts, Ot.sego Co., N. Y. 

 Fig. 26. A giitta-per(;ha impression of the preceding, enlarged. 

 Fig-. 27. A cast of a left valve faintly showing the surface striae and the anterior muscular scar, enlarged. 



Hamilton group. Shnre, of CanandaifftM lake, JV. Y. 

 Fig. 28. A left valve pi-esenting a slight variation in form, preserving the surface striae and showing the 

 crenulations of the hinge, enlai-ged. 



Lower Chemung group. Ithaca, N. Y. 



Pal.«;oneilo maxima. 



Page 335. 

 Figs. 29, 30. Two left valves presei-ving the surface striae. 



Hamilton group. Schoharie Co., N. Y. 

 Pig. 31. The right side of a cast of a specimen showing the large posterior muscular scar. 



Hamilton group. Schoharie Co., N. Y. 

 Fig. 32. A left valve showing an unu.sual elevation of the umbo from compression. 

 Fig. 33. A right valve showing a greater height than usual. 



Hamilton group. FHdtonham, N. Y. 

 Fig. 34. The cardinal view of the specimen fig. 31. 

 Fig. 35. An unusually short and broad right valve. 



Hamilton group. Shore of Cayuga lake, N. Y. 

 Fig. 36. The left side of a specimen preserving the two valves in conjunction. 



Hamilton group. Shore of Cayuga lake, N. Y. 

 Figs. 37, 38. Enlargements of hinge structure. The crenulations are erroneously represented, especially in 

 fig. 37. 



Pal.«;oneilo elongata. 



Page 345. 

 See Plate 93. 

 Fig. 39. A left valve showing the fine striae of growth, enlarged to two diameters. 

 Chemung group. Philipsburgh, N. Y. 



