184 INTRODUCTION TO ZOOLOGY. 



III. CEPHALOPODA CUTTLE-FISHES. 



Fig. 171. CALAMARY. 



IF we look at a Cuttle-fish (Fig. 171), we notice that the 

 head is surrounded by a number of appendages; and this 

 peculiarity is implied in the term " Cephalopoda"* It is 

 restricted to the third division of the encephalous Mollusca; 

 to that class which is the most elevated in organization. Its 

 superiority is manifested in the muscular, the respiratory, and 

 the nervous systems, and also in the existence of a true in- 

 ternal skeleton of a peculiar structure, the first approach towards 

 the most obvious characteristic of the vertebrate animals. 



Though the shell of the Pearly Nautilus (Nautilus Pompi- 

 Iins 7 Fig. 172) is common in museums, the capture of tho 



t 

 8 



Fig. 172. PEARLY NAUTILUS, WITH THE SHELL LAID OPEX. 

 Fig. 172 t, Tentacula. /, Funnel g, Foot. m, Fart of mantle. s, Eyo.- 

 , Siphon. 



* From two Greek words, signifying head-feet. 



