37 g THE COMMON PURPLE, OR PURPURA. 



more muddy parts of the coast, and prefer deep to shallow water. None of the Harp- 

 shells possess the operculum. 



The color of the Imperial Harp is pale chestnut and white, with a dash of yellow 

 arranged in tolerably regular and slightly spiral bands. 



THE smaller figure on the right-hand, having the animal attached, is the LITTLE 

 HARP-SHELL, a darker species, and one that seldom attains a greater length than an 

 inch and a half. This figure is given for the purpose of showing the peculiar foot, 

 which is very large, broad, and leaf-shaped, and, as will be seen by reference to the 

 illustration, has a deep fissure just behind the tentacles, nearly cutting the organ 

 asunder. It is said that, when the animal is irritated, the fissure becomes widely ex- 

 panded. Some writers say that, if the animal is very much terrified, it withdraws 

 itself into its home with such rapidity that the expanded front of the foot is unable to 

 contract sufficiently, so that the fissure is caught against the sharp front edge of the 

 shell, and thus undergoes involuntary amputation. 



The general colors are tolerably similar throughout the Harps, but each species 

 always preserves its peculiar individuality. One species, for example, has the spaces 

 between the ridges pencilled in elaborate wavy markings of chocolate on white, and 

 the ribs themselves barred at regular intervals by lines of deep brown ; while another, 

 known by the name of VENTRICOSE HARP (Harpa ventricosa), has the spaces filled with 

 a succession of arches, one within the other, and of a rich brown color. 



A VERY common shell may often be found on the seashore, looking like a small 

 whelk with a smooth whitish shell, boldly banded with reddish brown. This is the 

 COMMON PURPLE, or PURPURA (JP&rpura lapillus), another member of this genus, and 

 worthy of notice as being one of the shells which furnished the celebrated Tyrian 

 purple of the ancients. This color, which, by the way, contains so little blue as to be 

 unlike the tint which we now call by the name of purple, is evidently the analogue of 

 the ink found in the sepia, and is secreted in a little sac by the throat, containing only 

 one small drop. 



For the very best dye this material was extracted carefully from the individual shells, 

 but for an inferior kind it was obtained by pounding a quantity of the Purpurae in a 

 mortar, and straining off the juice, which was thus mixed with the blood and general 

 moisture of the animals, and consequently of less value than the pure dye. So expen- 

 sive was the dye obtained by this latter process, that a pound of wool stained with it 

 could not be purchased under a sum equalling thirty pounds of present money. Any 

 one can try the experiment of dyeing a little strip of linen with the matter obtained 

 from a single shell. After breaking the shell carefully so as not to crush the inhabit- 

 ant, the cell containing the coloring matter will be seen lying across the head or neck 

 of the animal, and can be removed by opening the sac and taking up the yellowish 

 white contents with a small camel's-hair brush, or the point of a new quill-pen. When 

 the linen is imbued with this liquid and placed in the rays of the sun, it immediately 

 begins to change its color, and passes through a series of tints with such rapidity that 

 the eye can hardly follow them, unless the slanting rays of the rising or setting sun 

 are chosen for the purpose. 



Light green is the first tint, which soon deepens until the yellow is driven out by the 

 mysterious power of light, and the substance assumes a blue color. After a while 

 another primary color makes its appearance, and a gradually deepening red being 

 diffused through it, the blue changes to rich purple. Even the blue, however, has a 

 comparatively feeble hold, for if the empurpled linen be well washed with soap and 

 water, and again exposed to the sun's rays, the blue gradually fades before the increas- 

 ing red, and a deepish crimson will be the ultimate result. Thus, we have the curious 

 phenomenon of a semi-liquid, almost destitute of color while shielded from light, assum- 

 ing in regular succession the three primary colors, first mixed so as to form the second- 

 ary tints, and gradually separating and retiring before the superior power of their 

 successors. 



The eggs of the PurpuraTnay often be found adhering to stones, shells, or even to 

 each other, by means of little footstalks, which give the object a singular resemblance 

 to an egg-cup with the egg placed in it 



i, 



