is eaten, is that in the scallop many portions are highly colored. 

 The visceral mass of the female is bright pink and the margins 

 of the mantle are usually very conspicuously colored with yel- 

 lows, browns, and black. Although such colors are not con- 

 sidered to be objectionable in many foods, they are not the 

 usual colors for " shell-fish " and accordingly are looked upon 

 with disfavor. 



SHELL. 



All members of the genus Pecten are provided with shells of 

 a very characteristic shape. The shells are rounded, inequi- 

 valved and eared ; the hinge line is straight and runs the length 

 of the margin formed by the ears, is not provided with teeth or 

 with a conspicuous hinge ligament and is provided with a large 

 cartilage that is placed immediately between the beaks of the 

 two valves. 



All of the members of the genus have somewhat similar habits, 

 are provided with numerous sense organs and are capable of 

 swimming by clapping the shell valves together. A very heavy 

 shell, massive teeth, or a small cartilage would not be adapted 

 for swimming in this manner, where lightness and speed of 

 movement are essential. A rounded outline is consistent with 

 such progression, and the presence of numerous sense organs is 

 important, for these animals live in positions unusually exposed 

 to the attacks of enemies. 



The shell of this particular species (figs, i to 7) is somewhat 

 longer than wide and rather flit. The dimensions of a good 

 sized specimen may be given as length 7 inches, width 65^ inches 

 and thickness i>4 inches. The proportional thickness differs 

 more than the other two dimensions, varying from a little under 

 1 14 inches to a little over 1% inches in specimens corresponding 

 to the other dimensions given. The two valves are of about the 

 same weight, but the right valve, that on which the animal 

 habitually lies, is much flatter than the left (fig. 19), lighter in 

 color and has a rather prominent rounded notch where the 

 anterior wing joins the main body of the shell (Hg. 4). I have, 

 been unable to satisfy myself as to the function performed 

 by this notch. The sense tentacles on the mantle margin oppo- 

 site the notch are somewhat longer than those adjacent, but I 



