PLATE XII. 
Glyptodesma erectum. 
Page 153. 
See Plates 11, 13, 25, 86 and 87. 
Fig. 1. A left valve. 
Hamilton group. Cdzenovia, N. Y. 
Fig. 2. A view of right valve showing pallial and muscular impressions. 
Hamilton group. Cazenovia, N. Y. 
Fig. 3. -A left valve preserving strong, concentric, lamellose surface markings. 
Hamilton group. Madison Co., N. Y. 
Fig. 5. A small right valve preserving the lateral teeth. 
Hamilton group. Schoharie Co., N. Y. 
Fig. 6. A very convex left valve. The radiating lines are represented too strongly in the figure. 
Hamilton group. Hamilton, Madison Co., N. Y. 
Fig. 7. The right side of a cast showing a very distinct muscular scar and pallial line. The apparent 
double impression of the muscular scar is probably due to an irregular growth of this part 
during its advancement. 
Fig. 8. A very large and erect left valve, with the cardinal angles much extended. It is of the form of 
Avicula cruciformis, Conrad. 
Fig. 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. 
Pig. 4. A small left valve nearly complete in form and outline. 
Hamilton group. Canandaigua lake, N. Y. 
