PLATK XIV. 

 Pterinea flabella. 



rage ii:i. 

 See Plates 15 and 83. 

 Fitr. 1. -V li't't valvi- (if a small siiofiiraeu of iiim-e than ii.«iial ohliqiiity. 



Hamilton {ri-oup. Eastin-n N. 1'. 

 Fig. 2. The left valve of anothei- speeimen, ^ven to sIkjw the ai>pearance produceil by having- a portion 

 of the mavfrin and wing removed. 



Hamilton group. Euateru N. Y. 

 Fi". 'i. A h'ft \alve of a well prewerveil specimen of medium size, showing the general form ami rhar- 



aiitere. Hamilton group. BaMern N. Y. 

 Fig. 4. .\ left valve somewhat narrower than the preceding. 



Hamilton group. PratVn Falls, Ommdaqa Co., N. Y. 

 Fig. f). A left valve having a broail body and extended ving. 



Hamilton group. Tiilli/, JS'. Y. 

 Fig. G. A large imperfect s))eiMmen with an unusually Jarge wing. 



Hamilton group, MililiKOil Co., S. Y. 

 Fig. 7. An impi-rfect left valve of nai-row, erect form, showing the striated ligamental area. 



Hamilton group. fSkniK'nlelfx lake, J\'. Y. 

 Fig. 8. The left side of a sjiecimen from whii'h the shell has been removed leaving only the marks of the 

 stronger radii in the cast, a (-onnuou cooilition of the .sp.-cimens from the hard calcareous layers. 

 Hamilton group. Delphi, JX^. Y. 

 Figs. 9-13. A series of right valves ; figs. 10, 11 and 12 beingthe reverse of tigs. 2, 8 and 5, respectively. 

 Fig. 14. A profile view of the specimen figs. 8 and 11, showing the comparative depth of the valves. 

 Fig. 15. The internal moidd of a right valve, showing the anterior and po.steriiir ninsiular impressions, 

 the jiallial line with the cardinal and lateial teeth. 



Hamilton group. Pratt'-i /allx, Onondaga Co.. N. Y. 

 Fig. 10. The interior tVom .'i gntta-percha mould, showing the form of the teeth and the uniscniar scars. 

 Figs. 17. IS. The vertical and cardinal views of a natural internal mould of a fragment of a left valve 

 showing the characters of the interioi-. 



Hamilton gi-onp. Otiego Co., N. Y. 

 Fig. 1".<. The interior, as obtained from a gutta-percha impres,sion. 

 Fig. 20. The internal mould of a snniU left valve preserving the hinge chariicters ami mu.scniar scara. 



Hamilton grouji. Ot.ttyu Co., iV. 1'. 

 Fig. 21. The inner surface of the carilinal portion of a left valve showing the ligamental ai-ea. 

 Hamilton group. Pratt'.i Falla, Onondaga Co., N. Y. 



