86 Laboratory Guide in Zoology 



cone. The body is not symmetrical, and in front of 

 the foot there is a head which bears the tentacles and 

 eyes. These animals are widely distributed : the 

 largest number live in salt water, but many live in fresh 

 water, and many are' terrestrial. Some breathe by 

 means of gills ; others by means of lungs. 

 III. — Cephalopoda. Cuttlefishes and Squids. 



This class includes the highest molluscs, the most 

 important examples being the Cuttlefish, Squid, Octo- 

 pus, and Nautilus. The members of it are bilaterally 

 symmetrical with the head separated from the body by 

 a slight constriction. There are two well-developed 

 eyes, a rasping tongue, a beak, and eight or more 

 tentacles. The ganglia of the head are somewhat pro- 

 tected by a covering. 



