i'LATE XX. 

 Leioptekia Conradi. 



Page 159. 

 Sefl Plate 8S. 

 Fijr. I- A liii's'*" l»'fl valve 



Ilamillim {jriiiip. Cniianda'it/ua laki; N. T. 

 Kifr. 2. A siiecimeu of iiieilium sizo showiiijf strong concenlric undulations. 



Hamilton gi'oup. liellona, Tatex Co., N. Y. 

 Kig. 4. A left valve. Another fig-iirc of this specimen is given on plate 88, fiy. a. 



Leiopteria Bigsbyi. 



Page lii,j. 

 8ee Plate 88. 

 Figs. 3, 11. Two left valves showing the form of the shell anil the line concentric stria;. 

 Figs. 13, 14. Two right \alves. 

 V\'S. 1"> A liirL'e left valve. 



Hamilton group. f>flio?iarie Co., i\". i'. 



Leiopteria l.evis. 



Page l.W. 

 See Plate 17. 

 Fig. 5. A left val\e enlarged to two diameters. 



Hamilton group. Ontario Co., N. Y. 



Leiopteria RAFiNEsyuii. 



I'age 161. 

 See Plates 15 and 88. 

 Fig. 6. A small left valve. 



Hamilton gi-oup. ISkaiieatdc.'i lake, N. Y. 

 Fig. 7. A largei- examjile showing regulai- concentric undulations of the surface. 

 ITaniilton grou)i. Biilona, Yotts Co.. .A''. Y. 



Leioitekia jMitciielij. 

 Page lee. 

 See Plate 88. 

 Fig. S. A left valve of this sjiecies. 



Hamilton groop. From a houldji- rra (hi: toicit, of Cathenne, Schuyler Co., j\'. Y. 



Leiopteria Greeni. 



Page IGO. 

 See Plat« 88. 

 Fig. t). A large imlividual retaining both valves partly opened, showing the left valve and the oardinal 

 \iew' of the I'ight valve. 



Hamilton group. BeUoua, Yate.1 Co., JV. Y. 

 Fig. 12. An imperfect left valve preserving a portion of the test and ^llowing the regular concentric 



lamella'. 



Hamilton grouj). -From ti boulder hi the town of Catherine, fiihnyhr Co., N. Y. 



IjEioitekia Oweni. 



Page 170. 

 Fig. 10. The specimen described, showing the right valve and the umbo of tlu' left. 

 Hamilton group. Cananrlnigiia lake, N. Y. 



Leiopteria Dekayi. 



Page 1(4. 

 See Plates 19 and 88. 

 Figs. 16-18. Tliree left \alves diflei-ing somewhat in form and obliquity. 

 Hamilton group. OUryo Co., JV. Y. 



Actinopteria decussata. 



Page 111. 

 See Plates 17, 18 and 84. 

 Fig. 19. A right valve. The speiMmen .shows the pallial line and nuiscular iniprc.«sion which features are 

 not i-ejircsenteil in the figure. 



Hamilton group. Mailison Co., iV. 1'. 



