Vlll CONTENTS. 



CHAP. VII. 



The Phytophagous Gastropods continued. — The TurbidaD, or Marine 

 Snails - - - ... Page 1V.'> 



CHAP. VIII. 



The Phytophagous' Gastropods concluded. — The Haliotidae, or Ear-Shells, 

 and the Naticidie, or Nerits - - . . £28 



CHAP. IX. 



On the Aberrant Tribes of the Gasteropoda, — namely, the .Scutibranchia, 

 or Limpets; the Cyclobranchia, or Chitons; and the Pteropoda, or 

 Crystal Shells - - - - - - 241 



CHAP. X. 



On the Order Dithyra, or Bivalve Shells — The Affinities and Analogies 

 of the Unionidas, or River Unios - _ . . 253 



PART II. 



A NATURAL ARRANGEMENT OF THE UNIVALVE AND BI- 

 VALVE SHELL-FISH COMPOSING THE ORDERS GASTERO- 

 PODA AND DITHYRA OF THE CLASS TKSTACEA - 29^ 



EXPLANATION OF TERMS USED IN DESCRIBING THE SHELLS 

 OF TESTACEOUS MOLLUSCA - - - 391 



APPENDIX - - - - 405 



