48 THE SCALLOP FISHERY 



shield of many a crusader, and that through all ages it has been regarded 

 as an object of beauty. 



Naturally, various questions on the subject of shell coloration arise, 

 such as (1) the nature of the coloring matter; (2) where and how it 

 appears; (3) the variations; (4) do scallops change color ? (5) is color 

 due to inheritance or environment? In connection with the growth 

 experiments on young scallops the following notes were made. 



Coloring Matter in the Shell. In scallops from 3 to 10 millimeters 

 the brown coloring matter is the predominating shade. When mounted 

 on a slide after having been treated with acid the colored shells leave a 

 brown outline of various intensities on the glass, according to the 

 depth of the color, while the pure white are barely discernible in outline, 

 showing that the brown coloring matter resists the action of the acid. 

 Other colors, as black and red, are of different origin and disappear 

 under the action of acids. 



The Appearance of the Color. The lower or right valve of the 

 scallop shows the color best. The upper valve is usually darker, of 

 plainer hue, and covered with growths such as eel grass, sea lettuce, 

 Enteromorpha and numerous smaller plant forms. In the young scal- 

 lops the color of the two valves is the same, and only when the upper 

 becomes coated over is any difference apparent. In the adult the lower 

 valve is much lighter in color than the upper. 



The time of appearance varies greatly. Albino scallops, which do 

 not seem to have any coloring matter in the shell, are found in all sizes 

 up to 1^2 inches. As they grow older the pure white color takes on 

 a yellowing or grayish hue. Scallops the size of the head of a pin may 

 have more color than scallops the diameter of a lead pencil. The pro- 

 dissoconch is unpigmented; occasionally in the dissoconch stage little 

 spots of color make their appearance, but no decided coloration takes 

 place before the plications begin to form, when the scallop assumes in 

 a minor degree the color patterns of the adult. 



Color Variation. The color of the shell varies greatly, especially 

 with the young. All varieties from a pure white to a grayish-black, 

 as well as a red variety, can be distinguished. The common marking 

 is a mottled or striped appearance, undoubtedly the intermediate forms 

 between the pure color types, as it is possible to arrange a series of 

 shells showing these gradations. The color marking of the young scal- 

 lops offers an excellent field for the student of variation. 



Young scallops from % to 10 millimeters can be readily divided into 

 two main classes, using color as a basis of separation. Some are dark 

 brown with a white fringe, while others range from a light yellow to a 

 transparent white. It seems strange that scallops of the same set and 

 size should present so much difference in color, and that different colors 

 are often found on the same place of attachment. 



In white scallops 2 to 3 millimeters a yellow pigment is frequently 

 found in the grooves between the ridges, whereas in the adults these 



