582 



INDEX. 



Fifth Class of Mollusca continued. 



Tectibranchiata . . . ... 



For the most part naked slugs 



Sea-hares 



Inferobranchiata .... 



Cyclobranchiata .... 



Limpets ...... 



Coat of mail-shell, chiton 

 Nudibranchiata .... 



Naked-gilled mollusca, common on the British coast 

 Their great diversity and beauty of form 

 Horned doris ..... 



Tritonia hombergi .... 



Young of nudibranchiate gasteropoda 

 Heteropoda ..... 



Their fin-shaped foot used as an oar 



CHAPTEK XIX. 



Sixth Class of Mollusca; 



Pteropoda ..... 



Their locomotive apparatus 

 Northern clio, its instruments of prehension 

 Limacina helicina, its exquisite shell 

 Hyalsea ...... 



Cleodora, its luminosity 



CHAPTER XX. 



Seventh Class of Mollusca : 



Cephalopoda ...... 



Their remarkable habits and appearance 



Their ink 



Mechanism of their suckers . 



Enormous size of some cephalopods 



The common poulpe, its terrible aspect . 



ltd powerful arms ..... 



Its chameleon-like change of colour 



Its amusing stratagems .... 



Calamaries, their additional arms 



Their plate of horn 



Squids, used for bait ... 



Their eyes ...... 



Hooked-squids, the tenacity of their grasp . 

 Cuttle-fishes ...... 



Common cuttles, their ink .... 



Cuttle-fish bone 



Eggs of the sepia . . 



The argonaut, fiction of the ancients respecting it 



Nautilus, its chambered shell 



Characteristic structure of nautilus 



Its food 



