380 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
them, and hence the nacre covers them so irregularly that it is not possible to make 
any use of them. From specimens exhibited it was shown that German Unios, as 
well as those of China, could be made to cover a plain relief with nacre. 
With the great abundance of Unio shells in North America, and their exquisite 
variety of tints, it seems as though a careful and judicious system of experiments 
might develop a form of art industry of great beauty and interest. 
One of the most singular circumstances connected with the New Jersey “pearl 
fever” of 1857 was the discovery of several shells which proved that local savants 
had experimented on the pearl-bearing Unios by dropping mother-of pearl buttons 
inside the shell, hoping that the mussel would cover them with its secretion. The 
specimens found had evidently been experimented on some thirty years previous, at a 
time whefi European scientists were greatly interested in shells received from China, 
which had been treated as above described. 
As further bearing on this point, although not in relation to fresh water shells, 
may be noted some facts brought out in the special report on pearl fisheries and pearl 
supply, in vol. n, No. 191, of the United States consular reports (August, 1890). 
In this article Mr. W. J. Weatherill, United States consul at Brisbane, Australia, in 
describing the pearl fisheries in Torres Strait, alludes to the local variation in the 
abundance of pearls in the pearl oysters, and states that the yield is much less where 
the bottom is muddy or clayey than where it consists of gravel or sharp sand. He 
also says that experiments are in progress for the production of pearls by artificial 
introduction of foreign substances, though as yet there has not been time to deter- 
mine how far they may be successful. 
Mr. A. E. Morland, consul at Belize, British Honduras, speaks of the pink pearls 
found in the large West India conch shell ( Strombus gigas), and mentions that these 
also can be artificially induced, though it is not done at that place. He refers to an 
instance, however, in which a person did succeed in this process, introducing a foreign 
nucleus through a hole bored in the shell, and thus obtaining conch pearls; but 
instead of being rewarded for his ingenuity the pearl manufacturer was brought 
before a West India magistrate and fined for fraud. 
Fresh water pearls have attracted attention more or less from very ancient times 
and in many lands. It would seem that pearls from Scotland, and perhaps other 
parts of northern Europe, must have been early articles of trade and barter with the 
Romans. Suetonius states that Caesar undertook his British expedition partly for 
the sake of finding pearls, and Pliny and Tacitus report his briuging home a buckler 
made of British pearls, which he dedicated to Yenus Genetrix and hung up in her 
temple. An account of the pearl fisheries in Ireland 1 was published, stating that 
oysters were found set up in the sands of the river beds, with the open side from the 
torrent. About one in one hundred would contain a pearl, and one pearl in one 
hundred would be tolerably clear. Between the years 1761 and 1764 the river Conway 
in Scotland supplied the London market with pearls to the value of £10,000 and fine 
Scotch pearls are still sold in London. The rivers of Cumberland, the Conway and 
the Tay in Scotland have yielded pearls that were noted for their beauty in times 
past, and they still continue to do so. In the United States consular report upon 
Pearls and Pearl Supply, vol. II, No. 191 (August, 1896), several references are made 
to these Scotch and Irish pearls as still in the markets of Europe, though not as being 
very fine. The Armagh River in County Tyrone and the Slavey River in County 
1 Trans. Royal Phil. Soc., 1693. 
