PEARLS AND PEARL FISHERIES. 55 



fisheries in West Australia are carried on in Sharks Bay. The 

 shells which are caught here are those of the Avicida margariti- 

 fera. They are very thin, but their inside surface is transparent, 

 and has a beautiful pearl-like lustre. At present they fetch a 

 good price at Havre. Formerly they were but little esteemed on 

 account of their thinness, and for this reason they were taken 

 principally on acount of their pearls. These have a brilliant 

 lustre, although they are not larger than a pea. The Oysters are 

 caught with a wire drag-net, which is drawn across the beds, and 

 which piles them in a heap ; thereby the mollusk is killed, and the 

 shells are easy to open. The West Australian pearl fisheries 

 increase from year to year. In 1874 mother-of-pearl was ex- 

 ported to the value of 1,060,707 crowns (284,269'48 dols.), and 

 pearls worth 108,000 crowns (28,944 dols.). In 1876 there were 

 exported to London 140 tons, and to Singapore 67 tons, the price 

 varying from 4500 to 4840 crowns (1206 to 1297-12 dols.) per 

 ton. Kecently the English papers have reported the discovery 

 of pearls and mother-of-pearl near New Zealand. 



Diving for pearls is one of the principal employments for the 

 natives of the Pacific Ocean. Here, likewise, mother-of-pearl is 

 the principal object of the fisheries. The Oysters live in large 

 colonies, close together, and are firmly attached to each other ; 

 they are attached to the bottom by a ligament or band, starting 

 from their body and running through the shell. In the live 

 animal this band is of a dark green, and sometimes gold-bronze 

 colour, and the fishermen can tell from its colour whether the 

 shells contain pearls or not. The shells reach their full size 

 when they are seven years old. The average weight of the 

 empty shell at that time is about one pound, and the length 

 varies from ten to eighteen inches. When the animal has 

 reached maturity, it tears itself loose from the stones, opens its 

 shell, and dies. The shells are then covered with corals and 

 parasites. They become worthless and the pearls are lost. 

 These mollusks also have a number of enemies, the most dan- 

 gerous of which is a kind of Scolopendra, which opens the 

 shells and eats the mollusks. All grown Mussels are, more- 

 over, infested by crustacean-like parasites, which penetrate into 

 the shells and there lay their eggs. 



After the Oysters have been caught and brought ashore by the 

 divers, they are sorted. The shells are opened with a steel knife. 



