Rich honesty dwells like a miser, sir, in a poor house, as your pearl in your foul oyster.

In geographic range, the sources of pearls are widely distributed, each one of the six continents yielding its quota; but the places where profitable fisheries are prosecuted are restricted in area. First in point of value, and possibly of antiquity also, are the fisheries of the Persian Gulf, giving employment ordinarily to thirty thousand or more divers. The yield in the likewise ancient fisheries of the Gulf of Manaar is uncertain, but sometimes remarkably large. The Red Sea resources are now of slight importance compared with their extent in the time of the Ptolemies. Other Asiatic fisheries are in the Gulf of Aden, about Mergui Archipelago, on the coast of China, Japan, Korea, and Siam, and also in the rivers of China, Manchuria, and Siberia.

Aside from those produced in the Red Sea and the Gulf of Aden, the pearl fisheries of Africa are of small extent. Some reefs exist on the lower coast of the German East African territory and also in Portuguese East Africa, but they have not been thoroughly exploited.

In most of the inshore waters of Australasia pearls may be secured; the fisheries are most extensive on the northern coast of Australia, in the Sulu Archipelago, and about the Dutch East Indies. Tuamotu Archipelago, Gambier, Fiji, and Penrhyn are prominent in the South Pacific Ocean.

In the seas of Europe few pearls have been found, but the rivers have yielded many; and although the resources have been greatly impaired, many beautiful gems are yet found there.

South America contributes the important reefs on the coast of Venezuela—the land of unrest and revolutions, whose fisheries were first exploited by Columbus. Other South American countries in which pearls are collected are Panama, Ecuador, Peru, etc. In North America, pearls are found in the pearl-oyster of the Gulf of California, the abalone of the Pacific coast, the queen conch of the Gulf of Mexico, and in the Unios of most of the rivers, especially those of the Mississippi Valley.

Since pearly concretions partake of the characteristics of the shell within which they are formed, it follows that practically all species of mollusks whose shells have a well-developed nacreous lining yield pearls to a greater or less extent. But the number of these species is relatively small. They belong chiefly to the MargaritiferÆ, or pearl-oyster family of the sea, and to the UnionidÆ, or family of fresh-water mussels. Pearls occur also in some univalves, but not so abundantly as in bivalves of the families mentioned. Broadly stated, we may hope to find pearls within any mollusk whose shell possesses a nacreous surface; and it is useless to search for them in shells whose interior is dull and opaque, such as the edible oyster for instance.

The great bulk of the pearls on the market, and likewise those of the highest quality, are from the MargaritiferÆ, which are widely distributed about tropical waters. Although these mollusks are spoken of as pearl-oysters, they are not related in any way to the edible oysters (Ostrea) of America and Europe.^[79] The flesh is fat and glutinous, and so rank in flavor as to be almost unfit for food, although eaten at times by the poorer fishermen in lieu of better fare. The origin of the name is doubtless due to the fact that in the somewhat circular form of the shell they resemble oysters rather than the elongated mussels of Europe, to which they are more nearly related in anatomy. Also in that—like their namesakes—they are monomyarian, having only one adductor muscle.

The two valves or sides of the pearl-oyster shell are nearly similar in shape and almost equal in size; whereas in the edible oysters one valve is thin and somewhat flat, while the other is thicker, larger, and highly convex. In the latter, also, the hinge, or umbo, is an angular beak; but in the pearl-oysters the umbo is prolonged by so-called ears or wings into a straight line the length of which is nearly equal to the breadth of the shell.

The byssus, or bunch of fibers, by which pearl-oysters attach themselves to the bottom indicates their relationship to the mussels. The possession of a small foot and somewhat extended migratory powers—at least in the first years of growth—also distinguish them from the sedentary edible oysters. But from an economic point of view, the principal difference is the possession of a thick, nacreous, interior lining in the shells of pearl-oysters, which is wholly lacking in the edible species. Like their namesakes, the pearl-oysters are exceedingly fertile, a single specimen numbering its annual increase by millions.

Commercially considered, the pearl-oysters are roughly divisible into two groups, (1) those fished exclusively for the pearls which they contain, and (2) those whose shells are so thick as to give them sufficient value to warrant their capture independently of the yield of pearls. The best examples of the first group are the pearl-oysters of Ceylon and of Venezuela, and to a less extent those of the Persian Gulf, the coast of Japan, and of Sharks Bay, on the Australian coast. Of the second group, the pearl-oysters of Torres Straits and of the Malay Archipelago are the most prominent members. Between these two groups are the many species and varieties whose shells and pearls are more evenly divided with respect to value, including those of Mexico, Panama, the Red Sea, the South Sea islands, etc.

Some conchologists recognize a large number of species of MargaritiferÆ, while other authorities consider many of these as local variations of the same species. There is much difference in the size, color, and markings of the shells in different localities, owing to varying geographical and physical conditions. The distinction of species and the nomenclature herein adopted are those of Dr. H. L. Jameson, who has recently revised and rearranged the collection of shells belonging to this family in the British Museum of Natural History,^[80] and to whom we are indebted for descriptive notes relative to several of the species.

The greatest pearl-producer in the family of pearl-oysters is the Margaritifera vulgaris of the Gulf of Manaar and the Persian Gulf, and to a much less extent of the Red Sea. It occurs in various other inshore waters of the Indian Ocean, and about the Malay Archipelago and the coast of Australia and New Guinea, although it is not the principal pearl-oyster of those waters. An interesting account of its immigration into the Mediterranean Sea through the Suez Canal was given by Vassel in 1896.^[81]

This species is quite small, averaging two and a half inches in diameter in Ceylon waters, and somewhat more in the Persian Gulf, whence large quantities of the shell are exported under the name of “Lingah shell.” The Ceylon variety has the nacreous lining almost uniformly white over the entire surface, only the lip having a slightly pinkish ground color. The exterior is marked by seven or eight reddish brown radial bands on a pale yellow ground. In addition to its greater size, the Persian variety is darker, and the lip of the shell has a reddish tinge.

For centuries the Margaritifera vulgaris has sustained the great pearl fisheries of Ceylon, India, and Persia, and at present yields the bulk of pearls on the market, especially the seed-pearls and also those of medium size. It produces relatively few large ones, rarely exceeding twelve grains in weight. These pearls are commonly silvery white, and for their size command the highest prices, because of their beautiful form and superior luster. Excepting the Venezuelan species, this is the only pearl-oyster which at present supports extensive fisheries exclusively for pearls; in the fisheries for all other species the value of the shells furnishes considerable revenue, and in some localities this represents several times as much as the income from the pearls.

Ranking next to Margaritifera vulgaris in extent of pearl production is the Margaritifera margaritifera, which is widely distributed about the tropical inshore waters of the Pacific and Indian oceans. It is very much larger than the Lingah oyster, good specimens measuring seven or eight inches in diameter, and the nacreous interior is usually of a darker color. In addition to its yield of pearls, the shell of this species is of value in the mother-of-pearl trade, and contributes largely to the economic results of the fisheries. Indeed, in several regions the shell is of more value than the pearls, which represent only an incidental yield. As Jameson notes, the color and markings of the shell, though extremely variable, generally suffice to distinguish this species. The ground color of the exterior ranges through various shades from yellowish brown to very dark brown. Its characteristic markings consist of from ten to eighteen radial rows of white and yellow spots, running from the umbo, or hinge, to the margin.

Several varieties of Margaritifera margaritifera are recognized. The type species occurs along the north coast of Australia, from Brisbane on the east to Sharks Bay on the west; on the New Guinea coast; at Formosa; and about many of the islands of the Pacific. The well-known “black lip shell” of Australian waters is of this species; it shows a greenish black on the margin of the nacre. The yield of this is very small compared with that of the large pearl-oyster of Australia.

The Margaritifera margaritifera occurs on the eastern coast of Arabia in two varieties, which differ somewhat from the type species. These have been designated by Jameson as M. margaritifera persica and M. margaritifera erythrÆensis. These are much larger than the Lingah shell of the Persian Gulf, but are smaller than the Australian species. The percentage of pearls in them is less than in the Lingah species, but from a commercial point of view this is to some extent offset by the greater value of the shell. The M. m. persica is more numerous in the gulf than the M. m. erythrÆensis, and large quantities of the shell are marketed in Europe. Formerly the shipments were made principally by way of Bombay, hence the shell is known in the mother-of-pearl trade as “Bombay shell.” The exterior is of a light grayish or greenish brown color, with yellowish white radial bands. The nacre has a slightly roseate tint, and the margin is greenish yellow. The pearls found herein are more yellowish in color and attain a larger size than those from the Lingah oyster.

The M. m. erythrÆensis occurs also in the Red Sea and along the shores of the Arabian Sea. Among mother-of-pearl dealers it is known as “Egyptian shell” or “Alexandria shell,” owing to the fact that prior to the opening of the Suez Canal shipments were commonly made by way of Alexandria. The color of the nacre is darker than that of its related variety in the Persian Gulf. In the trade, three grades of this shell are recognized, classed according to the shade of color. The lightest comes from Massowah and near the southern end of the Red Sea, and the darkest from farther north, in the vicinity of Jiddah and Suakim.

The islands of the southern Pacific, and of eastern Polynesia especially, yield another variety of M. margaritifera, to which the name M. m. cumingi has been given. The nacre is of a dark metallic green, and in the mother-of-pearl trade the shell is designated as “black-edged.” It attains a large size, only slightly smaller than the large Australian species; many individual specimens measure ten inches in diameter, and weigh six or seven pounds for the two valves. Belonging to this variety are those oysters whose shells are known in the markets of Europe and America as “Tahiti,” “Gambier,” and “Auckland” shells, the name designating the port of shipment.

Yet another subspecies, the M. m. mazatlanica, occurs on the coasts of Panama and Mexico, and especially in the Gulf of California. This is likewise green-edged, and the exterior color is yellow or light brown. This shell has been marketed in quantities since 1850, and is known in the mother-of-pearl trade as “Panama shell.” It is smaller than the Australian species, specimens rarely exceeding eight inches in diameter. It yields a large percentage of the black pearls that have been so fashionable in the last fifty years.

Since 1870, the largest pearls have been found mainly in a very large species of pearl-oyster, Margaritifera maxima, obtained off the north and west coasts of Australia, among the Sulu Islands, and elsewhere in the Malay Archipelago. In the fisheries for this species, the mother-of-pearl is the principal object sought, and the pearls are obtained incidentally. It is the largest of all the members of this family, reaching in exceptional cases twelve or thirteen inches in diameter, and weighing upward of twelve pounds; while the Ceylon oyster rarely exceeds four ounces in weight. So marked is this difference, that the Australian species is often designated the “mother-of-pearl oyster,” and the Ceylon species the “pearl-oyster.” Jameson notes that it differs from the Margaritifera margaritifera, its nearest competitor in size, in its much longer hinge, its shape, its lesser convexity, and in its color and markings. As described by him, the color ranges from pale yellowish brown to deep brown, with traces of radial markings of dark brown, green, or red in the umbonal area. In its marginal region, the shell is marked by a series of circumferential lines about one third of a millimeter apart.

Several geographical varieties of this species are recognized in the mother-of-pearl trade, differing principally in the coloring of the interior surface. The chief commercial varieties are “Sydney” or “Queensland,” “Port Darwin,” “West Australian,” “New Guinea,” “Manila,” “Macassar,” and “Mergui.” The nacre of those from the Australian coast is almost uniformly silvery white. That of the “Manila shell” is characterized by a broad golden border surrounding the silvery white nacre. The “Macassar shell” lacks the golden border of the “Manila shell,” and is similar in its uniform whiteness to the “Sydney shell,” but its iridescence is much greater.

The Margaritifera carcharium, from Sharks Bay, on the coast of Australia, yields yellow pearls and small quantities of mother-of-pearl. This species is small—three or four inches in diameter. The color is grayish or greenish yellow, with several somewhat indistinct radial bands of brownish green. The nacre has a yellowish green tint, with a margin of pale yellow, with brown markings.

In the West Indies and on the Atlantic coast of tropical America, especially the coast of Venezuela, occurs the Margaritifera radiata. This species is quite small, and seems to be closely allied to the Ceylon oyster. Like the latter, the nacreous interior is rich and brilliant, but owing to its small size, the shell is wholly valueless as mother-of-pearl. The principal and almost the only fishery for this species is on the Venezuelan coast, in the vicinity of Margarita Island, the islands of Cubagua, and Coche.

The coast of Japan yields the Margaritifera martensi, which occurs among the numerous islands in the southern part of the empire, but does not extend beyond 40° north latitude. This species is likewise small, and closely resembles the pearl-oyster of Ceylon, from which it differs principally in coloration. As noted by Jameson, brown and white predominate in the exterior coloring, and the interior of the lip is marbled with yellow ocher and chocolate brown, instead of pink, as in the Ceylon shell.

There are numerous other species of pearl-oysters, but they are of slight economic importance, and do not support fisheries of value.

As only a small percentage of the individual mollusks contain pearls, it follows that vast quantities are destroyed without any return whatever, and handling them merely adds to the expense of the industry, as well as reduces the resources of the reefs. This could be obviated if it were possible, without opening them, to determine the individual mollusks containing pearls.

Among the several methods proposed for this purpose, especially interesting is the use of X-rays, which was suggested by Raphael Dubois of Lyons, France, in 1901.^[82] The shells of some pearl-oysters—those of Ceylon and of Venezuela for instance—are relatively thin, and it was thought that by the means of the rays the presence of pearls could be ascertained, and non-pearl-bearers could be saved from opening, and be returned to the reefs without injury. Although the calcareous shell partly interrupts the radiations, it is not difficult to recognize the presence of large pearls.

The theory has never been found practical in application, owing largely to the rough and irregular exterior of the shell and the small size of the pearls. The presence of the larger pearls may be ascertained by this method; but it is exceedingly probable that a very large percentage of the small ones, and especially the seed-pearls, would be overlooked. Furthermore, if in their sixth year oysters contain no pearls, the probability of appearance therein later is very small, and little benefit would result from their return to the water. As to saving the trouble of opening the non-pearl-bearing mollusks, labor in the pearling regions is usually inexpensive, and this cost is far more than offset by the reasonable certainty of securing practically all the small as well as the large pearls by the present method of operation. Owing to the greater thickness and the economic value of the large pearl-oysters—as those of Australia or of Mexico, for instance—the application of X-rays to them is obviously impractical. However, when pearl-oyster culture becomes a highly developed industry, with personal ownership in those mollusks returned to the water, some method such as this might be of great value.

Pearls are yielded by various species of UnionidÆ or Naiades occurring in the rivers of America, Scotland, Saxony, Bavaria, Norway, Sweden, Russia, France, China, etc. These mollusks exist exclusively in the fresh-water streams, lakes, and ponds, and quickly die when submerged in salt water. The UnionidÆ are of particular interest in America, as it is here that this group is most abundant, and nearly every stream east of the Rocky Mountains contains more or less of them. The Mississippi basin abounds in Unios, or “clams,” as they are known to the fishermen of that region, and furnishes about 400 of the 1000 recognized species of this important family.

The Unios are most abundant in clear, running water, where the bottom is gravelly or sandy. The interiors of the shells are iridescent, and vary greatly in tint, exhibiting many delicate shades of color from silvery white to straw color, pink, purple, brown, etc.

About five hundred species of American fresh-water mussels have been recognized by conchologists. Many of these differ from one another so very slightly that they are scarcely distinguishable from an examination of the shells themselves, or even from the descriptions, and a detailed index to the complete list is of little economic importance. The professional fishermen and the shell-buyers take the trouble to name only the species with which they deal, which includes only about twenty-five species, all of which are margaritiferous, though some to a greater extent than others. In the pearling regions a popular nomenclature exists, the names given by the fishermen having reference to the shape, color, etc.

The niggerhead (Quadrula ebena) is the most numerous in the Mississippi, and it is extensively used in button manufacture. The thick shell of this species is almost round, with a black outer surface and a pearly white interior. At maturity it averages about four inches in diameter and four ounces in weight. Owing to its uniform whiteness and the flatness of its surface, it is well adapted to button manufacture, and for this purpose more than twenty thousand tons are taken in the Mississippi Valley every year. When the fishery originated, the niggerhead was very abundant in some places, and especially between La Crosse and Burlington. From a single bed near New Boston, Illinois, measuring about 200 acres in area, 7500 tons, or about 70,000,000 individual shells, were removed in three years. In 1897, a bed of 320 acres near Muscatine furnished 500 tons, or about 4,750,000 shells. This species occasionally yields valuable pearls.

Two species of Unios, Quadrula undulata and Q. plicata, are known among the fishermen as “three-ridges.” The former is also known as the “blue-point” from the fact that the sharp edge is usually tinged faint blue on the inside. Although not the best for button manufacture, the shells yield the greatest number of pearls.

A species somewhat similar to the niggerhead is the bullhead (Pleurobema Æsopus). This shell is thick and opaque, the nacre is not so iridescent as that of the niggerhead, nor does it yield pearls of such good quality. These two species are not evenly distributed over the bottom of the streams, but occur in great patches or beds, sometimes several feet in thickness and covering many hundreds of acres. Some of the beds are several miles in length, and they may be separated by twenty or thirty miles in which the mollusks are so scarce that profitable fishing can not be made; but usually the reefs are smaller and more closely situated.

The sand shells (Lampsilis)—of which there are several species—do not occur in large beds, but are scattered over the sandy beaches and sloping mud-banks. In shape they are narrow and long, adults measuring five or six inches in length. Owing to the small waste in cutting, due to uniformity in thickness, these shells are sold to button manufacturers for more than the niggerhead, which in turn is more valuable than the bullhead.

The buckhorn (Tritigonia verrucosa) is very long and narrow; on the dark brown exterior it is rough, as is the horn from which it takes its name, while the interior shows a beautiful display of colors. This is not found in beds, but lies scattered among other species. It sells at a relatively high price—usually in excess of $20 per ton—for button manufacture.

Another species is the butterfly (Plagiola securis), which is very prettily marked on the outside with faintly colored dotted stripes of varying length. Over a background of dark yellow run black stripes to the outer edge of the shell, with dark dots between the stripes. The shell is small and thick, and like the sand shell and the buckhorn, is found in small quantities. Owing to the beauty and permanency of its luster, this shell is in demand for button manufacture, and its pearls are often very beautiful.

Other well-known species are the pancake (Lampsilis alatus), the maple-leaf (Quadrula wardi), and hackle-back (Symphynota complanata). On the Atlantic seaboard, the principal species in which pearls have been found are Unio complanata; the Alasmodon arcuata, which has hinge teeth, and a species of Anodon. Pearls from the Unio complanata are usually smaller but more lustrous than those from either of the other species.

Among the many fresh-water mussels are found some remarkable conditions of animal life. Probably the most curious is the parasitic stage of certain species. When hatched from the egg, each one of these is provided with hooks or spines, by means of which it attaches itself to the gills or fins of a swimming fish and becomes embedded therein. After confinement in this cyst for a period of two months or more, the small mollusk works its way out and falls to the bottom of the river or pond, where its development continues along lines more conventional to molluscan life.

In most of the species of Unios the sexes are separate; but it has been determined that in some the individuals are provided with both sets of sexual organs. It is claimed by some naturalists that certain species may change from one sex to another; yet this does not seem to have been positively established.

Not the least interesting of the habits of the Unios is the manner in which they “walk,” bushels of them changing their habitation in a few hours. The shell opens slightly and the muscular tongue-like “foot” is thrust out, and by pressure of this on the bottom, the mollusk is propelled in a jerky, jumpy movement with more speed than one would suppose possible for the apparently inert creature.

The number of eggs produced by an individual in one season ranges from a few hundred in some species to many millions in others, as in the Quadrula heros, for instance. Most of the fresh-water mollusks are of slow growth, reaching maturity in six or eight years, and it is believed that if undisturbed they live to be from fifteen to fifty years old; indeed, some writers credit them with attaining an age of one hundred years.

While outwardly there is no positive indication of the existence of pearls, they are relatively scarce in young mollusks, and likewise in those having a normal, healthy appearance, with smooth exterior free from blemishes, and they are found generally in the older, irregular, and deformed shells, which bear excrescences and the marks of having parasites. However, some of the choicest pearls have come from shells relatively young and apparently in perfect condition.

It has been pointed out that with the fresh-water Unios there are three indications on which the fishermen to some extent rely for determining the presence of pearls from the outward aspects of the shell. There are, first, the thread or elevated ridge extending from the vertex to the edge; second, the kidney-shape of the shell, and third, the contortion of both valves toward the middle plane of the mollusk.

A single mollusk may contain several small pearls,—more than one hundred have been found,—but in such cases usually none has commercial value. Ordinarily only one is found in the examination of very many shells. Of these objects it may be truthfully said that “many are found, but few are chosen,” few that are of first quality or are worthy of a fine necklace. In many instances, several pounds of cheap pearls would be gladly exchanged for a choice gem weighing an equal number of grains.

On the Atlantic seaboard of America, the Anodontas, or “mussels,” as they are known locally, are more numerous than the Unios. They prefer the still waters of the ponds and lakes, rather than the swift currents of the streams. The shell is much thinner than that of the Unios, and it is usually not so brilliant in color and iridescence; consequently the pearly concretions obtained from them are less lustrous.

The rivers of Europe, and of Asia also, contain numbers of pearl-bearing mussels. In many localities the yield of pearls has at times attracted attention and produced much profit, though probably never equaling the present extent of the Mississippi River finds. The principal pearl-bearer of Europe is the Unio margaritifera, the shell of which has been of some local importance in the manufacture of pearl buttons. In Great Britain it is known as the pearl-mussel; in France as the moule or huÎtre perliÈre; in Germany as perlenmuschel; in Belgium as paarl mossel de rivieren; in Denmark as perle-skiael; in Sweden as perlmussla; in Russia as schemtschuschuaja rakavina, and in Finland as simpsuckan cuosi. The Unio margaritifera likewise exists in Siberia, and possibly elsewhere in Asia. Other species of Unio exist there and in Mongolia, Manchuria, etc., as, for instance, U. mongolicus, U. dahuricus, etc. A leading species in eastern China, the Dipsas plicatus, has long been extensively employed in the artificial production of pearly objects or culture pearls.^[83] Unio pearls show less uniformity of tints than those derived from the pearl-oysters. They present an extended series of shades, corresponding to those on the interior of the shells, from almost perfect white through various tints of cream, pink, yellow, bright red, blue, green, russet, and brown. The metallic shades are numerous, especially the steels and the coppers.

Most of the members of the MytilidÆ family, which includes the marine mussels, are of slight luster; and the pearly concretions found in them are of the grade known as “druggists’ pearls,” so-called because, formerly, they were used in a powdered form in astringent and other medicines. However, some of these mussels on the European coast yield pearls that are fairly lustrous. The white and the pink are most numerous, but purple, red, bronze, and yellow are by no means uncommon.

A few pearls are also obtained from the sea-wings or wing-shells (Pinna), the silkworms of the sea, found in the Red Sea, the Mediterranean Sea, the Indian Ocean, the southern coast of America, and elsewhere. These shells are narrow at the umbo, or hinge, long, and fan-shaped; they are generally brittle, and present a horn-like appearance. The interior is commonly of a silvery reddish or orange-colored hue, and this tint is imparted to the pearls. The most characteristic feature of the Pinna is the thick rope of silky fibers, from four to ten, and sometimes twenty or more inches in length, constituting the byssus, a remarkable provision by means of which it anchors itself to the bottom and thus outrides the storm. Formerly the byssus was gathered in Sicily, washed in soap and water, dried, corded, and fabricated into gloves and similar articles of a fine texture. The finished garments were of a beautiful golden brown color, resembling the burnished gold on the backs of some splendid flies or beetles.

The yield of Pinna pearls is very small. A few are obtained from the Mediterranean, especially on the Adriatic coast. These are usually rose-tinted or reddish in color, but of diminished orient, and inferior in size. Pinna pearls are also reported from the Isle of Pines and from New Caledonia, where they are commonly very dark, almost black in color.

The window-glass shell (Placuna placenta), the vitre chinoise of some writers, yields a few small, irregularly shaped pearls of a dull leaden color. It occurs in the inshore waters of the Indian and the southwestern Pacific oceans; fisheries are prosecuted in Tablegram Lake, near Trincomali, on the northeast coast of Ceylon; on the coast of Borneo, especially at Pados Bay, and to a less extent in some other localities. This mollusk is quite distinct from the true pearl-oyster, and in adult life is devoid of the byssus, living on the muddy bottom of the shallow waters. The shell is almost circular, the right valve is quite flat, and the left only slightly convex. It is remarkable for its transparency, especially in the first year of growth, when the beating of the heart of the mollusk is visible through it. Reaching maturity in about two years, the shell becomes white and translucent, resembling pressed isinglass somewhat in its texture. It then measures about six or seven inches in length, and nearly the same in width. The outside is rough; the interior is glazed over and has a subdued pearly luster. It is so thin and transparent that with a strong light very coarse print can be read through it. It is commonly used in the East Indies as a substitute for glass in windows, admitting a soft mellow light into the room. For this purpose it is usually cut into small rectangular or diamond-shaped pieces, about five or six square inches in area, and these are inserted into sash frames. It forms a good economical substitute for glass, not only in windows of native residences, but also in lanterns and the like.

The giant clam (Tridacna gigas) of tropical waters yields a few large opal-white symmetrical pearls, with faint luster and of little value. The transversely oval shell of the Tridacna, with its great squamous ribs, is probably the largest and heaviest in existence, single pairs weighing upward of 500 pounds. It is found in tropical seas, and especially in the Indian Ocean. It is much used for ornament, particularly for fountain-basins, and for bÉnitiers, or holy-water fonts. A beautiful pair used as bÉnitiers in the Church of St. Sulpice in Paris is said to have been a gift of the Republic of Venice to Francis I. There seems to be no established fishery for this mollusk, and the pearls very rarely come on the market. About four years ago in New York City an effort was made to market one weighing about 200 grains. The owner represented that it was a “cocoanut pearl,” and offered to sell it for $2000; whereas its actual value was probably not over $10 or $20, and that only for a museum collection.

Pearls of slight luster also occur in the quahog, or hard clam (Venus mercenaria), of the Atlantic coast of the United States. Although these are rare, they are generally of good form, and some weigh upward of eighty grains each. They are commonly of dark color, purplish, ordinarily, but they may be white, pale lilac, brown, and even purplish black, or black. The white ones—which so nearly resemble ivory buttons as readily to pass for them at a casual glance—are of little value; but fine dark ones have retailed at from $10 to $100 each. There is little demand for them, for unless the color is very good, they possess slight beauty, lacking the orient peculiar to choice pearls. Pearls have also been reported from the edible clam of the Pacific coast of America.

Shelly concretions are found in the edible oyster of America (Ostrea virginica), as well as in that of Europe (O. edulis); but these are commonly objects of personal interest or of local curiosity, rather than of artistic or commercial value, as they are lacking in luster and iridescence. Most of them are dull or opal-white, some are purple, and a few are white on one side and purple on the other. As many as fifty of these formations have been found in a single oyster. Sometimes they are of odd appearance, suggesting the human eye or face, and recently one was found which bore a striking resemblance to a human skull. Notwithstanding many news items to the contrary, it is doubtful whether the choicest pearl from an edible oyster would sell for as high as $20 on its own merits; professional shuckers have opened thousands of bushels of oysters without finding one which would sell for ten cents.

Among univalves, the most prominent pearl-producer is probably the common conch or great conch (Strombus gigas) of the West Indies and the Florida coast, which secretes beautiful pink pearls of considerable value. This is one of the largest of the univalve shells, some individuals measuring twelve inches in length, and weighing five or six pounds. The graceful curves and the delicate tints of lovely pink color make it exceedingly attractive. The conch abounds in the waters of the West Indies, especially in the Bahamas, where many thousands are annually taken for the shell, which forms quite an article of commerce. The flesh is esteemed as food and is also used for bait; and it is particularly in preparing for these purposes that the pearls are found, as no established fisheries exist for the pearls alone.

The ear-shells or abalones (HaliotidÆ) found on the coasts of California, Japan, New Zealand, and other localities in the Pacific, secrete pearly concretions, sometimes with fine luster, but usually of small value. These shells resemble in general outline the form of the human ear. Distinguishing characteristics are the flatly-spiral bowl-like shape, and the regular series of holes in the back near the distal margin, for the admission of water to the respiratory organs. The holes are on the left side and parallel with the columellar lip, and those nearest the apex close up as the shell increases in size. The shells are rough externally, but beautifully nacreous within. In variety and intensity of coloring, the nacre is superior to that of the pearl-oysters, but it is not so harmonious, and it does not form so thick and flat a layer.

Abalone pearls are especially interesting on account of their brilliant and unusual colors. Green predominates, but blue and yellow also occur. Although commonly very small, some of the well formed ones exceed seventy-five grains in weight, and those of irregular shape may be very much larger. The ear-shells also produce many irregular pearly masses. Although these are without an established commercial value, their beautiful greenish or bluish tints adapt them for artistic jeweled objects, such as the body of a fly or of a beetle.

Similar concretions are found in species of turbos and turbinella, especially the Indian chank (Turbinella rapa), which yields pink and pale red pearls. The pearly nautilus (Nautilus pompilius) yields a few yellowish pearls, especially those taken in Australian waters; but from the paper nautilus—“the sea-born sailor of his shell canoe”—no pearls are obtained, owing to the non-lustrous nature of the shell.

In bygone days, especially in Asia, and also to some extent in Europe, pearls were credited as coming from many non-molluscan sources. The Rabbis had the idea that they came also from fish, as noted in the story of a tailor who was rewarded by finding a pearl in one which he bought (Gen. R. xi. 5). The Raganighantu of Narahari, a Kashmir physician of about 1240 A.D., reported them as coming from bamboos, cocoanuts, heads of elephants, bears, serpents, whales, fish, etc.;^[84] although it conceded that these were deficient in luster, which is recognized as the characteristic feature of pearls. We understand, therefore, that this use of the word signifies only hard concretions of a spherical form. In the apology for his book, prison-bound Bunyan wrote:

The crystal gems—the diamonds, rubies, etc.—are practically unlimited in their longevity, existing thousands of years unchanged in condition. Except those which have been discovered by man, the earth contains about as many as it ever did, and it is not unreasonable to suppose that in course of time a considerable percentage of the total will be discovered. But in the seas as well as in the rivers, the longevity of pearls is greatly restricted, and

to run their course of existence and decay unseen and unknown. Perishable while in the seas, almost as cereals and fruits on land, the harvest must be gathered with promptness or it is wasted. And it seems probable that only a small percentage of the beautiful gems produced in the waters have gladdened the sight of man.

With considerable hesitancy we have attempted to estimate the number of persons employed in the pearl fisheries of the world, and the aggregate local value of their catch. For two or three regions, this is not a matter of great difficulty. For instance, the divers employed in the Ceylon fishery are numbered each season, and the auction sales of their catch furnish a reasonably satisfactory basis for determining the value of the output. Likewise in Australia, Venezuela, and some minor localities, the fishermen are numbered; but the reports are less satisfactory as to the value of the pearls. In the Persian Gulf, the Red Sea, the Gulf of California, and the islands of the Pacific, where pearl-diving is a profession and a regular source of livelihood, the number of employees is fairly constant. But in the rivers and ponds of America, as well as of Europe and of Asia, where neither experience nor costly equipment is required for the industry, and pearls to the value of very many thousands of dollars are obtained by men, women, and even children, on pleasure bent, as well as in the widely fluctuating professional fisheries, the problem is far more difficult.

Contending with these many difficulties, we venture to present the following estimate of the number of persons employed in the pearl fisheries of the world, and the value of the output in 1906.

Our returns do not represent the annual output of pearls in the values best known to gem buyers. The difference in price between pearls in the fisherman’s hands in the Persian Gulf or at the Pacific islands, and that for which they are exchanged over the counters in New York or Paris, is nearly as great as the difference in value of wool on the sheep’s back and of the same material woven into fashionable fabrics. For each dollar received by the fisherman, the retail buyer probably pays three; and it is not unreasonable to suppose that the pearls herein represented probably sold ultimately for an aggregate of $24,420,000.

This summary falls far short in giving a correct idea of the importance of the pearl fisheries in furnishing a livelihood to humanity; for it takes no consideration of that great body of men who contribute incidentally to the prosecution of the fisheries, such as shell-openers, pearl-washers, watchmen, cooks, laborers, etc. In the Ceylon pearl fishery of 1906, for instance, our estimate shows 18,500 fishermen; but there were 40,000 persons engaged at the pearl camp alone, and many others were given employment in boat-building, supplying provisions, selling the pearls, etc., and this does not include the wives and children depending on the industry for sustenance. Indeed, it seems not unreasonable to estimate that instead of only the 18,500 fishermen, 85,000 persons were in a large measure dependent for their livelihood on the Ceylon fishery in 1906.

Estimated on the same basis, we have a total of 500,000 persons depending largely on the pearl fisheries of the world for their support. Thus we see that pearl buyers and pearl wearers not only gratify a commendable admiration for the beautiful, but contribute largely to the economic balance whereby one class of humanity either sustains or is dependent upon another, even though these classes be so widely separated as the crown of Russia from the half-starved diver of the tropical seas. How strange is the providence of God, who, by granting the pearl to the poor Arab, the Tamil of India, the South Sea Islander, and the forgotten Selang of Mergui, makes the greatest and wealthiest in the world contribute to their support.