A LAND SNAIL AND OTHER MOLLUSKS 



165 



Cephalopods. - - The cephalopods are all marine mollusks. 

 The commonest species along our eastern coast is the squid (Fig. 

 94, A). Squids are spindle-shaped animals that swim about 

 freely by means of a pair of fins that wave gently up and down, 

 or propel themselves rapidly in any direction by means of a jet 

 of water forcibly driven from a movable tube, the siphon, sit- 

 uated just beneath the head. Their food consists of small fish, 

 Crustacea, and other squids which are captured and held by 

 means of ten tentacles provided with suckers. The squid's 



--8 



--9 



7-' 



1- 



FIG. 95. The chambered nautilus. 



1, last completed chamber of shell; 2, hood part of foot; 3, shell muscle; 

 4, mantle cut away to expose, 5, the pinhole eye; 6, outer wall of shell, partly 

 cut away to show chambers; 7, siphon; 8, lobes of foot; 9, funnel. (After 

 Kerr.) 



eyes should be mentioned, for they are very large and resemble 

 somewhat those of human beings. 



The relatives of the squid that are perhaps most interesting 

 are the chambered nautilus and the octopus. There are only a 

 few living species belonging to the genus Nautilus. The cham- 

 bered or pearly nautilus, Nautilus pompilius (Fig. 95), lives on 

 the bottom of the sea near certain islands of the South Pacific. 

 The shell is spirally coiled in one plane and Is composed of com- 

 partments of different sizes, which were occupied by the animal 



