xii TABLE OF CONTENTS. 



PTEROPODA, of the Palaeozoic formations — (Continued) : page. 



Htoi.itiiks: Historical sketch 191-193 



Distribution of species 193-195 



Descriptions of species 195-202 



Clatiirwxklia : Generic features and description of species .... 203, 204 



Conulari a : Historical sketch 205-207 



Geological distribution 207, 208 



Descriptions of species 208-216 



CEPHALOPODA, of the Palaeozoic formations 217-478 



Orthoceras: Historical sketch 217-226 



Subgeneric, stratigraphical and geographical relations .... 226-230 



Distribution of species 230-232 



Orthocerata of the Schoharie grit 233-264 



Orthocerata of the Upper Helderberg limestone 264-271 



Orthocerata of the Hamilton group 272-304 



Orthocerata of the Portage group . 304-308 



Orthocerata of the Chemung group 808-314 



Bactrites: History, and description of species 315-317 



Gomphoceras : Historical sketch, distribution and generic relations . . 318-320 



Descriptions of species 321-353 



Ctrtoceras : Generic reference and historical sketch . . - . . . 354, 350 

 Gyroceras : Relations of species and historical sketch .... 358-360 



Ctrtoceras : Description of species 360-373 



Gtrocera8 : Descriptions of species ........ 373-389 



Trochocbras : Historical sketch and distribution 390, 391 



Description of species 392-403 



Nautilus : Historical sketch 404-406 



Description of species / 407-424 



Nautilus, subgenus Discites : Descriptions of species 425-430 



Goniatites : Historical sketch 431 432 



Descriptions of species 433—478 



ADDENDA ET CORRIGENDA 479, 480 



INDEX 481-192 



