PLATE XII. 



Glyptodesma ekectum. 



Page 153. 



See Plates 11, IS, 25, 86 and 87. 

 Fig. I. A left valve. 



Hamilton group. Cazenovia, X. Y. 

 Pig. _. A view of right valve showing pallia! and muscular impressions. 



Hamilton group. Cazenovia, X. Y. 

 Fig. :>. A left valve preserving strong, concentric, lamellose surface markings. 



Hamilton group. Madison Co., X. Y. 

 Pig. 5. A small right valve preserving the lateral teeth. 



Hamilton group. SchoJiarie Co., X. Y. 

 Pig. 6. A verj convex left valve. The radiating lines an' represented too strongly in tin- figure. 



Hamilton group. Hamilton, Madison Co., X. Y. 

 Fig. 7. The right side of a cast showing a very distinct muscular scar and pallia! line. The apparent 

 double impression of the muscular scar is probably due to an irregular growth of this pari 

 during- its ad\ ancement. 

 Pig. 8. A. very large and erect left valve, with the cardinal angles much extended. It is of the form of 



Avicnla eruriformU, Conrad. 

 Pig. 9. A very large left valve with the test partially exfoliated. 



Hamilton group. Jefferson. Schoharie Co., N. Y. 



Glyptodesma erectum, var. obliquum. . 



Page 155. 

 See Plate 13. 

 [•"eg. t. A small left valve nearly complete in form and outline. 

 Hamilton group. Canandaigua lake, N. Y. 



