CONTENTS OF YOL. IV. 
Preface .....^.. vii 
Introductory remarks upon the Upper Helderberg, Hamilton, Portage and Che¬ 
mung groups, with list of genera noticed in the volume. 1- 4 
Genus Lxngtjla and descriptions of species of the genus. 5 - 15 
“ Discina “ “ « ... 15 - 26 
“ Crania “ « “ of the genus.... 26- 30 
“ Pholidops « “ « “ .. 31-32 
“ Orthis “ “ “ « . 33-63 
“ Streptorhynchus “ “ “ .... 64- 75 
“ Strophomena “ “ “ .... 76-77 
“ Strophodonta “ « « ... 78-114 
“ Chonetes : observations upon and descriptions of species of the genus 115 - 145 
“ Productus and Strophalosia : observations upon the genera....... 146 - 153 
Subgenus Produotella and description of species. 153-185 
Genus Spirifera and descriptions of species of the genus.. 186-257 
Subgenus A^iboccelia and descriptions of species..... 258 - 262 
Genera Cyrtia and Cyrtina : observations upon. 263-265 
Descriptions of species of Cyrtina... 265-271 
Genus Trematospira and descriptions of species... 271-276 
“ Rhynchospira and description of species. 276-278 
“ Nucleospira “ “ . 278-281 
“ Athyris and observations upon. 282-285 
“ “ descriptions of species of... 285 - 294 
“ Meristella and observations upon. 295 - 299 
“ “ descriptions of species of. 299- 
Subgenus Pentagonia. ....... 309 - 
Genus Atrypa and descriptions of species. 312-327 
“ Ccelospira and description of species. 328-330 
Family Rhynchonellid^e .. 331 
Genus Rhynchonella. .... 332 - 334 
Subgenus Stenocisma... 335 
« “ descriptions of species. 335 - 354 
Genus Leiorhynohus and descriptions of species. 355 - 364 
“ Leptoc(ELIA and description of species. 365-366 
« Camarophoria “ “ ... 367-368 
Observations on the Genera Pentamerus, Pentamebella, Stricklandinia, 
Amphigenia, RensseljERIA, etc...... 369 - 374 
