440 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



own aud other countries, as exhibited at Chicago, and their actual and possible uses 

 for oruauieutal work. 



At the Tiffany Pavilion in the Manufactures Building there was a collection illus 

 tratiug the occurrence of pearls and the various pearl-bearing shells and inollusks — 

 notably a series of several thousand odd-shaped aud curiously-formed pearls, pearl 

 blisters, and hinge pearls, from the Unios of Wisconsin, Texas, Tennessee, and Ohio. 

 In this collection are found round, oval, oblong, aud mallet-shaped Unio pearls; two 

 pearls ingrown into one another; pearls consisting of scarcely more than a blister, 

 others formed of a single nacreous layer, with a central arc of clay, and other curious 

 and abnormal growths, of interest to the naturalist, but of little commercial value 

 (see PI. 31). A silver tea-pot incrusted with fresh water pearls (see PI. 28). A speci- 

 men of the fresh-water mussel Margaritana margaritifera, from the Botova River in 

 Bohemia, carefully prepared and injected, showing a pearl in place between the mantle 

 and the shell (see PL 41). A series of Unios from the Sugar River, Wisconsin (see 

 Pis. 35 and 36), and from Texas, Tennessee, and Kentucky, remarkably large; a 

 heart-shaped pearl, very nearly an inch in length (see PI. 31), from the true pearl oyster 

 of Ceylon, interesting as being hollow throughout. (This type has been frequently 

 observed, notably in a collection of this kind presented by Mr. M. Lowensten to the 

 Imperial School of Mines at St. Petersburg.) A pearl oyster was shown with a para- 

 sitic fish, Fierasfer, from Lower California (see PI. 32) ; a pair of pearl-oyster shells 

 remarkable for their size, weighing 151.35 ounces (see PI. 37), from the west coast of 

 Australia; a pearl-oyster shell from Tahiti, having attached to it three forms of coral, 

 one of them a group 8 inches in height and 8 inches in width ; the mollusk had 

 lived, notwithstanding this great burden, although one of the corals at the side had 

 very nearly suffocated it by closing the shell of the animal at the time when it was 

 captured (see PI. 29). A shell found on the coast of New Guinea had on it a cup 

 shaped coral over 8 inches in diameter and 6 inches in height. (For a series of similar 

 specimens, see PI. 30.) 



There are also other examples where pearls are imbedded in the shells themselves, 

 and some (see PI. 31) where pearls had been imbedded and dropped out; also abnor- 

 mally large growths in the shell (see PI. 33), some of them more than an inch in diame- 

 ter and an inch in height. These forms are frequently cut over and used as baroque 

 pearls. Another form is a curious inclusion at the point of the shell, where the muscles 

 are attached to the valves. This has the appearauce (see PL 33) of the eyes and mouth 

 of an ape's head. A small piece of the true mother-of-pearl shell two fifths of an inch 

 in length, which broke while undergoing the operation of being made into a button, 

 revealing a small inclosed crab (see PL 32) immediately below the blister; a collection 

 of pearl blisters assuming imitative shapes; and a large pearl-oyster showing the 

 perforations of some marine borer which the mollusk has covered (see PL 39). 



Other exhibits in this series were a group of four pearls united in a heart-shaped 

 form (P1.3i,E); several hundred pearls from the abalone shell, Haliotis rufescens, from 

 the Gulf of California; a collection of various species of Haliotis, one containing an 

 immense interior growth resembling a camel's head (see PL 38), due to some external 

 injury (measuring 2i by 2 inches) ; a collection of fine pearls from the large pink conch 

 of the Bahamas, Strombus gigas, varying from deep pink to almost pure white, one of 

 the pearls measuring nearly an inch in length; one small conch pearl and the shell in 

 which it was found, from the coast of Florida; pearls from the U uios of Weymouth, Nova 



