348 THE PEARL OYSTER. 



a bird. The interior of the valves is pearly, and the exterior layer is composed of a kind of 

 mosaic work of five or six sided particles. This structure is easily to be seen by means of a 

 moderately powerful simple lens, merely by holding up a scallop or other shell before the 

 -window, so as to allow the light to pass through it. 



A dark, whitish species is the curious HAMMER-SHELL. Only for the oddity of its form, 

 which somewhat resembles that of the hammer-headed sharks, it attracts some attention. As 

 it lies on the ground, it would hardly be taken for a shell by one who was not acquainted with 

 it, the enormously expanded ears and strangely crumpled valves giving it a most unshell- 

 like aspect. This strange form is, however, only to be seen in the adult specimens, or when 

 young. The shape of the Hammer Oyster is very like that of the pearl Oyster, presently to be 

 described. 



THE VARIEGATED SCALLOP is, in common with many other mollusks, able to move with 

 considerable swiftness by means of repeated strokes of its valves, a single stroke carrying it 

 for several yards. 



The animal is very beautiful, its color being orange or fine scarlet, and the mantle marbled 

 with brown of different hues. A series of round black dots, called ocelli, and thought to 

 answer the purpose of eyes, are ranged around its edge, and surrounded by long, tentacular 

 filaments. like the Oyster and mussel, the Scallop is considered as a delicacy, and eaten 

 dressed in various ways. The shell is of little value, its chief use in these days being as a 

 vessel in which Oysters are "scalloped ; " but in the ancient times it was in great request, as 

 the sign of one who had made a pilgrimage to the shrine of St. James. When at rest, the 

 Scallop lies on the right valve. 



The family Pectinida, or Scallops, follows in order. The Pecten irradians, or Common 

 Scallop, is much used in New York and southern part of New England as an edible. The 

 adductor muscle alone is used. It is prized by many, but is not uniform in its effect on 

 others ; while some dislike its sweetish taste. 



THE well-known PEARL OYSTER is one of the most valuable of the shell-bearing mollusks, 

 furnishing the greater part of the pearls which are set by jewellers and worn by ladies. The 

 specimens represented in the engraving are half as large as in their natural size. These 

 creatures are found in Ceylon, Madagascar, Swan River, Panama, etc. Not only the pearls 

 themselves are valuable, but the shells are of great importance in the commercial world, 

 furnishing the best "mother-of-pearl," as the nacreous lining of the valves is called. 



The pearls are secreted by the animal in precisely the same manner as the nacre of the 

 shell, and are, indeed, the same substance, formed into a globular shape, and disposed in con- 

 centric layers, so as to give that peculiar translucency which is quite indescribable, but is 

 known among jewellers by the name of "water." As to the precise method and object of 

 their formation opinion differs, the general impression being that they are morbid secretions, 

 often stimulated originally by a grain of sand or some such substance finding admission into 

 the shell. These objects may be obtained by introducing into the shell certain extraneous 

 bodies, around which the nacre is secreted so as to form very good imitations of the pearls 

 formed after the usual manner. Examples of such artificial pearls will be mentioned in the 

 course of the following pages. 



The Pearl Oyster does not produce its costly harvest under six or seven years of age, and 

 it is, therefore, a matter of importance that the bed should be so managed that the young 

 Oysters may be suffered to remain in peace until they have attained an age which renders them 

 capable of repaying the expense of procuring them, and that no part of the bed should be 

 harried where the Oysters are too small to produce pearls. It is hoped that the increasing 

 knowledge of the mollusk and its habits will enable proprietors to sow the sea with pearls just 

 as they sow a field with grain, and that the harvest may be equally certain in either case. 



The Oysters are now obtained by means of men who are trained to the business, and who 

 can remain under water for a considerable time without being drowned. Each diver takes 

 with him a net bag for the purpose of holding the Oysters, puts his foot into a stirrup, to 



