I1.ATE cxr. 



Trochoceras obliquatum. 



Pago 401. 



See Plate 58. 



Fig. 1. Ui>i>er lateral view of a fiagment, ehowirig' the curvature of the tube and the depth of the air- 



chaniliers. Schoharie grit. Schoharie, N. T. 

 Fijf. 3. A nejituui of the preceding, showing the transvei-se section of the tube and the position of the 

 siphuncle. 



Trocuoceras Pandion. 



Page 400. 

 See Plate 58. 

 Fig. 8. Lateral view of a septate fragment, sh<iwing the curvature of the tul)e, the dopth of the air-chambei'S 

 and some traces of the furrows of the crenulations continued over the internal mould of the 

 walls of the air-chambers. Schoharie grit. Schoharie, N. Y. 



GONIOCERAS ? PANDCM. 

 Page 403. 

 Fig. 4. A fragment imbedded in the surrounding rock, showing one of the angles of the tulie, the variation 

 in the depth of the air-chamtieif, and the curvature of the sutures over the broad, flat faces of 

 the tube. Schoharie grit. Schoharie, N. Y. 



Trochoceras expansom. 



Page 403. 

 See Plate 58. 

 Rg. 5. Dorsal view of a portion of a small individual, showing the form of the shell and the transverse 

 section nf the tube, with the siphuncle on the convex ventral side. The slight departure from 

 a synimetrical coil, and its nautiloid character, are also indicated. Schoharie grit. Scho- 

 harie, N. Y. 



Trochoceras Clio. 



Page 39-2. 

 See Plate !>9. 

 Fig. 6. The upper side of a small individual, showing oblique annulations, with the septa at i-ight angles to 

 the spiral axis, and crossing the annulations. Schoharie grit. Schoharie, N. Y. 



Trochoceras Biton. 



Page 395. 

 Rg. 7. A Ihigment showing the curvature of the tube, and the linear nodes which are prominent on the 

 concave dorsal side, and extend aa rounded, transvei-se undulations to the convex ventral side. 

 The surface-markings are pi-eserved over a small portion of the tube, and show as strong longi- 

 tudinal strice. Schoharie grit. ClarksvUle, N. Y. 



Trochoceras Barraudbi. 



Page 898. 

 yf Fig. 8. -The siphuncle of a specimen which has broken longitudinally along the ventral line, and exposed the 



siphnncular tul>e, showing the amount of its expansion in the cavities of the air-chambere, and 

 the striations of its surface at the constrictions where it passes thi-ough the septa, Schoharie 

 giit. C'larksvilU, N. Y. 



