ECONOMIC ZOOLOGY 411 



closed in pearl, it having entered the shell for protection. 

 Coarser pearls occur in other species. Occasionally valu- 

 able ones are found in the river-mussel ( Unio) of our Amer- 

 ican streams. Other mollusks, as the abalone on the Pacific 

 coast and the Unio, furnish material for buttons or for in- 

 laid work. The large scales of certain fishes (as the tarpon) 

 serve a similar purpose. The shells of many small 'sea-snails 

 are used as beads, and shells of mollusks as well as skins of 

 birds have been used as money by native aboriginal races. 



The fine furs above enumerated are largely used for 

 ornament rather than for use. The plumes of various 

 birds, notably the ostrich and the egret, are used for orna- 

 ment. Dead birds and parts of birds have been worn as 

 ornaments on the hats of unthinking women of even civil- 

 ized races. Incalculable injury has been done through this 

 fashion by the destruction of insect-eating birds. The sing- 

 ing-birds of Japan have been practically exterminated by 

 the remorseless demands of the milliner, and those of our 

 own country have been greatly reduced in number. Re- 

 cently our statutes have protected our own singing-birds, 

 but the remorseless destruction of parrots and egrets in 

 Mexico and of terns and other beautiful sea-birds for orna- 

 mental purposes still goes on. 



323. Animal products used in the arts. Chief among the 

 animal products used in the arts is leather. This is de- 

 rived chiefly from the skins of the ox, sheep, and goat, but 

 that of the horse, hog, deer, and many other animals, native 

 and domestic, has a certain value. Waterproof shoes are 

 made from the skin of the hair-seal. The skin of the alli- 

 gator is often tanned for portmanteaus, and the skin of 

 snakes for purses. 



Oil is procured from many animals. The fine oil from 

 the liver of the codfish is largely used in medicine, being 

 readily assimilated. Coarser oils are produced from other 

 fishes, especially from the liver of sharks. Still coarser oils 

 are taken in large quantities from the blubber of the right 



