234 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



appendages of the head. The head is more or less definitely 

 set off from the rest of the body. The eyes are large and highly 

 developed. The main part of the foot is composed of a series 

 of eight or ten freely movable tentacles or "arms" surrounding 

 the mouth. These arms are provided with numerous sucker- 



FIG. 109. A devil-fish, Polypus apollyon. (Much reduced.) 



like discs which enable the animals to hold fast to the rocks or 

 to catch and hold their prey, for they are all carnivorous. 



The devil-fishes, genus Octopus (Polypus), have only eight 

 arms and so are known as Octopods. These arms or tentacles 

 may attain a length of fifteen feet or more, and with their great 

 sucker-like discs form very effective means of offense or de- 

 fense. The body is sub-spherical and without a shell. Their 



