: COMPARATIVE ANATOMY 



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C. LAMELLIBRANCHIA . . . . . . .61 



D. CEPHALOPODA ....... 67 



V. ARRANGEMENT OF THE ORGANS IN THE MANTLE CAVITY, AND 



or THE OUTLETS OF INNER ORGANS IN THAT CAVITY . 71 



A. GASTROPODA . . . , . . .71 



B. SCAPHOPODA ....... 80 



C. LAMELLIBRANCHIA ....... 81 



D. CEPHALOPODA ....... 81 



VI. THE RESPIRATORY ORGANS ...... 84 



THE TRUE GILLS OR CTENIDIA ..... 84 



A. AMPHINEURA ..... .86 



B. GASTROPODA ....... 88 



C. LAMELLIBRANCHIA . . . . . . .91 



D. CEPHALOPODA ....... 96 



ADAPTIVE GILLS ....... 97 



LUNGS ........ 99 



VII. THE HYPOBRANCHIAL GLAND ..... 101 



VIII. THE HEAD ... . 101 



A. GASTROPODA ....... 102 



B. SCAPHOPODA . . . . . . .104 



C. CEPHALOPODA . . . . . . .105 



IX. THE ORAL LOBES OF THE LAMELLIBRANCHIA . . . 105 



X. THE FOOT AND THE PEDAL GLANDS . . . .106 



A. AMPHINEURA ....... 106 



B. GASTROPODA ..... .107 



C. SCAPHOPODA .... 112 



D. LAMELLIBRANCHIA ....... 112 



E. CEPHALOPODA . . . . . . .115 



XI. SWELLING OF THE FOOT (Turgescence) . . . .118 



XII. MUSCULATURE AND ENDOSKELETON .... 119 



A. AMPHINEURA . . . . . . .120 



B. GASTROPODA . . . . . . .120 



C. SCAPHOPODA . . . . . . -.123 



D. LAMELLIBRANCHIA . . . . . .124 



E. CEPHALOPODA ....... 126 



XIII. THE NERVOUS SYSTEM .... . 128 



A. AMPHINEURA . . . . . . .128 



B. GASTROPODA 132 



