V: CONTENTS. 



PAGE 



ORDER III. OPISTHOBRANCHIATA .... 385 



SECTION A. TECTIBRANCHIATA . . . 386 



SECTION B. NUDIBRANCHIATA . . . 388 



ORDER IV. HETEROPODA . . . . 390 



CHAPTER XVII. 

 OF THE CLASS OF PTEROPODA ..... 394 



CHAPTER XVIII. 



OF THE LAMELLIBRANCHIA.TE CONCHIFEKA . . 397 



ORDER I. ASIPHONATA ..... *397 



SECTION A. OSTRACE^E ib. 



SECTION B. PECTINID^E .... 401 



SECTION C. MARGARITACE^S . . . 402 



SECTION D. MYTILACE^E .... 405 



SECTION E. UNIONID.E .... 407 



SECTION F. ARCACE^E . 408 



ORDER II. SIPHON ATA .... 409 



SECTION A. CHAMACE^E .... ib. 

 SECTION B. CARDIACE^E . . . .411 



SECTION C. VENERACEJE .... 413 



SECTION D. PHOLADACE^E . . . ib. 



CHAPTER XIX. 



OF THE CLASS OF PALLIOBEANCHIATA .... 420 

 CHAPTER XX. 



OF THE CLASS OF TTJKECATA ..... 424 



ORDER I. ASCIDLE ..... 429 

 ORDER II. SALPJE . . . . .433 





 CHAPTER XXI. 



OF THE CLASS OF POLYZOA 436 



