PLATE XI. 
Glyptodesma erectum. 
Page 153. 
See Plates 12, 13, 25, 86 and 87. 
Pigs. 1, 2. Two opposite valves of the same individual. Fig. 2 shows the muscular scar and also gives 
the comparative elevation of the beaks of the two valves. The left valve of the specimen 
also shows the pallial line and muscular impression, which are not represented in the 
figure. 
Fig. 3. A more entire left valve, having the ears but little extended. 
Fig. 4. A right Valve having the cardinal angles much produced. 
Hamilton group. Fultonham, Schoharie Co., N. Y. 
Fig. 5. A smaller right valve, showing one of the oblique lateral teeth. 
Hamilton group. Cazenovia, N. Y. 
Fig. 6. A right valve, showing a proportionally greater breadth and moderately extended cardinal 
expansions. 
Fig. 7. A portion of a large left valve with very large cardinal alations. 
Hamilton group. Madison Co., N. Y. 
Fig. 8. A left valve. Another figure of this specimen is given on plate 86, fig-. 6. 
Hamilton group. Cazenovia, JY. Y. 
Fig. 9. A large left valve with short broad cardinal angles and unusual height. The impression of the 
ligamental area is longitudinally striated. 
Fig. 10. A left valve with the cardinal angles narrow and unusually extended. This form is the Avicula 
cruciformis, Conrad. Ann. Rep. p. 54, 1841. The specimen preserves the pallial line and 
muscular impression, which are not shown in the figure. 
