PLATE LXXXV—Continued. 
Ptychopteria Beecheri. 
Page 143. 
Fig. 2L. An entire left valve showing its gibbous and arcuate form. 
Fig. 22. A right valve of this species. 
Chemung group. Warren, Pa. 
Ptychopteria lata. 
Page 145. 
Fig. 23. An entire left valve. 
Fig. 24. A larger left valve. . 1 
Fig. 25. A right valve showing its comparatively strong alar fold. 
Chemung group. Warren, Pa. 
Ptychopteria alata. 
Page 139. 
See Plate 23.' 
Fig. 26. The posterior half of .a‘left valve, showing the subangular posterior slope. 
Chemung g-roup. Salamanca, N. T. 
Ptychopteria Eucrate. 
. Page. 133. 
v See Plate 23. 
Fig. 27. A left valve of this species. 
Fig. 28. A small left valve. 
Chemung group. Panama, N. Y. 
Ptychopteria Galene. 
Page 142. 
Fig. 29. A left valve flattened by pressure. 
Fig. 30. A smaller left valve preserving- the normal proportions of the species. 
Fig. 31. The right valve of a specimen preserving.both valves. 
Chemung group. Warren, Pa. 
Ptychopteria Thalia. 
Page 148. 
Fig. 32. A small right valve. 
Fig. 33. A medium sized left valve showing the short gibbous form of the shell. 
Chemung group. Alleghany Springs, Warren Co., Pa. 
Ptychopteria trigonalis. 
Page 140. 
Fig. 34. A small left valve showing the form and characters of the species. 
Fig. 35. A large imperfect left valve. 
Chemung group. Panama, N. Y. 
Ptychopteria Vanuxemi. 
Page 151'. 
Fig. 36. A portion of a large left valve, showing the peculiar form of the body and the surface characters 
Chemung group. Warren, Pa '. 
Ptychopteria lobata. 
Page 150. 
Fig. 37. A left valve showing the short form of the valve and the strong alar plication. 
Chemung group. Warren, Pa. 
Ptychopteria perl at a. 
Page 147. 
Fig. 38. A right valve of this species.' •' 
Fig. 39. A left valve showing the form and surface markings. 
Chemung group. Warren, Pa. 
