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 but rarely sold in market, their 
flesh being little esteemed as food, more than 1,000,000 pounds of 
squids valued at about $14,500 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 
the fishermen as “‘sea-grapes.” 
The Blunt-Tailed Squid, (Loligo pealit, Fig. 115). 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, (Ommastrephes illecebrosus). 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, (Architeuthis princeps, Fig. 116). 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 off 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 
