PLATE C. 



Gyrocer\8 VAt-IDrit. 

 Page 385. 

 See Plate 49. 

 Fig. 1. Lateral view of an iTidividual pi-eservin(f nearly its natural form ; showing the curvature and eularge- 

 inent of the tube, and the gradual increase in the depth of the air-chambei-s, from the apex 

 toward the gi-and chamber. The direction of the chamber of habitation is outward from the 

 spiral in a direction tangent to the curve. At the apei-ture the tube is slightly expanded. 

 Schoharie gi-it. Albany county, N. Y. 



