PLATE LXXXVII. 



Glyptodesma erectum. 



Puge lij. 

 See Plates 11, 12, 13, 25 and 86. 



Fig. 1. The interior of a specimen with the valves thrown open, showing the c parative size and form 



of the valves, the hinge characters and muscular markings. 

 Hamilton group. Delphi, Onondaga Co., IV. 1*. 

 Fig. 2. The internal mould of a left valve, showing tin- pallial line, muscular impression and small tuber- 

 cles in the inter-pallial area, representing the points of attachment of small umbonal muscles. 

 Hamilton group. Pratt's falls. Qrion'&aga Co., 2\'. Y. 

 Fig. 3. An internal mould of a right valve showing the anterior and posterior adductor muscular impres- 

 sions, and a small Crania attached to the wing. 



Hamilton group. Prom a loulder, Waverly, Tioga Co., N. 1". 



Pal eopinna flabella. 



Page 210. 

 See Plate 25. 

 Fig. 4. The left valve described, showing the form of the shell and a single' groove along the hinge. 

 Oriskany sandstone. Schoharie, IV. Y. 



Ptekonites inoptatus. 



Page 239. 

 Fig. 5. A left valve showing the form of the shell. The scar on the post-umbonal slope was produced by 

 the attachment, of a Crania. 



Chemung group. Mansfield, Pa. 



