1 42 Descriptive Zoology. 



ending in the mantle cavity near the large inner end of 

 the funnel. The excrement, as in the clam, is swept out 

 by the water current. There are salivary glands ; and a 

 large digestive gland, often called the "liver," pours its 

 secretion into the cecum. 



How the Squid captures its Prey. The squid is a 

 voracious animal and lives largely on small fishes. It 

 sometimes stealthily approaches a fish by almost imper- 

 ceptible motions of its fins, until it is within grasping dis- 

 tance, when it suddenly seizes the fish and quickly kills it 

 by biting it in the back of the neck. Again it swims 

 swiftly, and suddenly darts among a school of fishes, and 

 turns and kills its prey by a quick snap .of its powerful 

 jaws. It also eats crabs and other animals. While it is 

 pursuing the smaller fishes, it may, in turn, be chased by 

 larger fishes. 



Respiration and Circulation in the Squid. The squid 

 has two plumelike gills attached to the under surface of 

 the body, extending along the mantle cavity. The circu- 

 latory system is more highly developed than in any of 

 the other mollusks. 



The Nervous System. The nervous system, too, is 

 highly developed and concentrated, consisting of several 

 pairs of ganglions in the head, forming a central brain, 

 from which nerves extend to the other parts of the body. 

 There is a protecting case of cartilage, a rudimentary cra- 

 nium, supporting and partly surrounding the brain. 



The Senses of the Squid. The eyes are highly devel- 

 oped, and evidently have keen sense of sight. A number 

 of squids may be lying side by side in the water, perfectly 

 motionless, perhaps relying on their quietness and protec- 

 tive color. A sudden motion on the part of a person ob- 



