PLATE LIX. 



Trochoceras Clio. 



Pnge 392. 

 See Plate 111. 



Pig. 1. The apper siile of the internal mould of an individual, showing the depth of the air-chambers, and 

 the extent of the grand chamber. The impression of one of the inner volutions is retained, 

 showing the surface ornaments. 



Fig. 3. The umbilical side of an individual, showing the diameter of the umbilicus, and the annulations and 

 revolving striie of the test. The septal sutures are less frequent, and oblique to the annulations. 



Fig. 3. Profile view of the preceding, showing the deflection of the volutions. 



Fig. 4. The coniyive dorsal siile of the chamber of habitation, showing the transverse section of the tube j 

 the position of the small siphuncle which is 8urrounde<l by an obscure areola, and the surface- 

 characters on the inner side of the volution. 



Fig. 5. A small individual nearly entire, showing the form of the shell, the number of volutions, and the 

 height of the spire. 



Fig. 9. A large individual, showing the 'numerous continuous a-inulationa, and the gradually enlarging- 

 tube. The annulations are rounded on the outer volution, and are wanting on the chamber of 

 habitation. The specimens of this species are from the Schoharie grit, at Schoharie, N. T, 



Trochoceras discoideum. 



P«ge3M. 

 Fig. 6. Upper lateral view of a small individual, showing the depressed spire, the enlargement of the tube, 



the linear, transverse, annular nodes, and the revolving strite of the test. 

 Fig. 7. The same view of a larger specimen, showing stronger undulations of the tube, with several septa 



near the apex. 

 Fig. 8. The umbilical side of an example, showing the rapidly enlai-ging tube and the broad, shallow 



umbilicus. Schohaiie grit. Schoharie, N. T. 



Trochocbras edqenium. 



Pll^t9«. 



See Plate 58. 

 Fig. 10. A view of the upper lateral side of an individual, pre8er\-ing the grand chamber and a part of the 



septate portion, the whole forming a little moi-e than an entire volution, and showing the outer 



half of the grand chamber produced beyond the inner volution, in a straight tine, and not 



following the curvature of the spiral axis. 

 Pig. 11. A similar view of a larger individual, showing the gibbous form of the shell and the contraction of 



the tube towai-d the aperture. Schoharie grit. Schoharie, N. Y. 



