MOLLUSKS 161 



surroundings, while at times flushes of steely-blue, purple, reddish 

 or yellow flash over the body as the creature swims. 



These changes of color are produced by the contraction and 

 expansion of several sets of pigment cells beneath the skin. For 

 example, — when the reddish-brown set contracts, the brown color 

 is so reduced that it almost disappears, whereas the expansion of 

 these pigment cells instantly tinges the whole surface. 



Although these creatures are biit rarely sold in market, their 

 flesh being little esteemed as food, more than 1,000,000 pounds of 

 squids valued at about $1J:,500 are taken annually upon the Massa- 

 chusetts coast, to be used in the cod fishery, and about one-half of 

 the bait used upon the banks of Newfoundland consists of squids. 



Squids lay their eggs upon weedy bottoms throughout the 

 summer, the eggs being contained in clusters of gelatinous finger- 

 shaped capsules, each capsule holding a large number. These 

 clusters are often five or six inches in diameter and are known to 

 tiie fishermen as "sea-grapes." 



The Blunt-Tailed Squid, (Lal'ujo pcalii. Fig 115 J. This is the 

 common squid from the Carolinas to Cape Cod. North of this point 

 it is rare, and it does not extend beyond Cape Ann, Massachusetts. 

 It becomes about a foot in length, and is usually speckled with 

 rusty-brown or purplish color, although its color constantly changes 

 in intensity. The fin is large, obtusely rounded on the outer 

 edges, and about as broad as it is long. A closely allied pale 

 translucent variety called Loligo pealii var. pallida is most abund- 

 ant in Long Island Sound. 



The Short-Tailed Squid, {Om mast replies illecebrosiis). This is 

 the common squid of the New England coast north of Cape Cod, 

 and is most extensively used as bait in the cod fishery. The fin is 

 one-third broader than it is long, and its outer edges form nearly a 

 right angle. 



The Giant Squid, ( Areliiteuthis princeps, Fkj. 116 J. This is the 

 largest living invertebrate, and the sudden appearance of its 

 writhing arms upon the ocean has probably given rise to stories of 

 the sea serpent. It has been seen but rarely, and then always 

 upon the Grand Banks or ofP the coast of Newfoundland. Alto- 

 gether not more than thirty specimens have been found, and the 

 majority of these were badly damaged. The arms are as thick as a 



