PLATE XCIIl. 



GoMPnOCERAS RUDE, 

 rage S-i7. 

 Fif . 1. Ventral view of the specimen, showingr the crenulated band, the depth of the ur-ch&mbci's, and the 

 Bipbuncle, aa exposed from the process of weathering. The specimen preserves more of the 

 chamber of habitation than is represented in the figiira. The curvature and sinus in the niai'* 

 gia, aa represented in the lig'ure, do not belong to the apertui-e. Schohaiie grit. Sdio- 

 Jorie, N. T. 



GOMPHOOEKAB OLAVATOM. 



Page 8-23. 



See Plate 46. 



Fig. 2. Ventral view of an individual, showing the characters of the chamber of habitation, near the aper- 



tui-e. Schoharie grit. 

 Fig. 3. A large, compi-essed individual, referred with doubt to this species, but preserving several of the 

 specitic charactera. Schoharie grit. Schoharie, N. Y. 



GOMPBOOERAS CRUCIPERUM. , 



Page Zm. 

 Fig. 4. A septum, showing the transver-se section of the tube and the peculiar cruciform ornamentation 

 around the siphuncle, sun'ounded by indistinct strise. The upper, narrower end of the sep- 

 tum is probably the concave side of the tube. Schoharie grit. Schoharie, N. Y. 



GOMPHOCERAS TUMIDUM. 



Page 351. 



See Plate 95. 



Kg. 6. A fragment of the chamber of habitation, near the aperture, showing the slight sinus in the margin, 



coiTesponding to the small apertui-e. 

 Fig. 6. A fragment of an individual, showing the ventricose chamber of habitation and the depth of the 

 air-chambers. Chemung group. Ithaca, N. Y. 



GOMPHOCERAS POOULUM. 

 Page 340. 

 Fig. 7. A portion of an individual, somewhat compressed, showing the variation in the depth of the air- 

 chambers, and the furrows of the crenulations continued over the walls of the chambers. The 

 furrows do not extend over the grand chamber toward the aperture, as i-epresented in the 

 figure, the internal mould of this portion being essentially smooth. 

 Kg. 8. The opiK)site side of the apical portion of the preceding, showing the elements of the siphunclei aa 

 exposed from weathering. Hamilton group, near Cazentma, N. Y. 



GOMPHOCERAS SOLIDUII. 

 Page 338. 

 Fig. 9. A large portion of an, individual, showing the form of the shell and the depth of the ur-cbambers. 

 The change of the slope of the sides from the point of greatest gibbosity is more abrupt than is 

 represented. The specimen also shows the crenulated zone, and the crenulations extending 

 over the cast of the walls of the air-chambers. Qoniatite limestone. ManLiaa, N. Y. 



