Cephalopoda. 141 



escape are greatly increased. This ink is the original 

 "sepia" used as ink by the Chinese and Japanese. Some 

 of this ink, from the fossil squid, has been used to make a 

 drawing of the animal from which the ink was taken. 



The Color of the Squid. Ordinarily the dead squid is 

 of a pale color, tinted with purplish. In the living animal 

 the color is very changeable, passing quickly from red to 

 blue or purple, and one part may have one of these colors 

 while other parts have another color. This change of color 

 is due to several different sets of colored cells, called "chro- 

 matophores"; these expand and relax under the control 

 of muscles, which are in turn governed by nerves. The 

 color changes in quick flashes, exceeding the quickness of 

 blushing and pallor observed in the human face. This 

 change of color is undoubtedly for the sake of protection, 

 though one is inclined to wonder why such intense hues 

 should be employed. As a school of squids are swimming 

 along they are often seen to change their color abruptly, 

 according to the bottom over which they are passing. 



Methods of Escape from Enemies. (i) The squid may 

 elude observation by taking on the color of its surround- 

 ings. (2) By speedy flight. (3) In flight its chances of 

 escape are increased by the discharge of ink, which makes 

 the water turbid. 



The Digestive System. The brown beak projects from 

 the center of the circle of arms in front of the head. It 

 consists of a pair of hard, horny jaws, somewhat resem- 

 bling the beak of a parrot, except that the upper jaw 

 is much smaller than the lower, into which it shuts. 

 In addition to the beak there is a lingual ribbon, as in the 

 snails. From the mouth extends a long, narrow gullet. 

 Well back in the body is the muscular stomach, which 

 has a large cecum. The intestine then extends forward, 



