286 BULLETIN OF THE BUREAU OF FISHERIES. 



partitioned or marked areas, each of which contains a special lot as regards size and 

 age, and give one an idea of the most methodical procedure. 



It has been found that the crop of tiny shells which can he collected each season 

 differs greatly in amount with different years. For instance, in L893 the crop was 

 very large, amounting to 14,1-15 bushels, hut in the following year there were only 

 L5 bushels, and in the two years after that matters were still worse, there being prac- 

 tically none at all. In order, therefore, to have the market supply constant and not 

 fluctuating as these " seed" shells, it has been found possible to retard the growth of 

 the shells. That is, after they reach a size of 2,000 to a "sho" they are removed to 

 a somewhat deeper place, where the current is slow and where the}' are no doubt also 

 kept more crowded than usual. This has been found enough to make their growth 

 slower, and the seed shells collected in one year can thus he depended on to supply 

 the market for five years. 



The 3-year old sin lis are exported in the fresh condition to China, where they 

 are very much valued, while the 4-year old and the older are consumed in Japan. 



Another species of Area (.1. sitberenata Lischke) is cultivated more or less in the 

 same Kojima Bay, but this shell flourishes best in deeper waters which are not exposed 

 at low tide and wlic: - ^ seaweeds are growing. Such a condition is found in N'akano- 

 I'mi near Matsui. , 'nee Isumo. on the Japan Sea side, where the ark-shell has 

 now been cultivated for over a hundred years. The system of culture is that of rotary 

 crops, giving line results. The area under cultivation is at the present day about 

 2,631 acres. 



THE RAZOR CLAM, "AGEMAKI." 



Solecurtus constricta Lamarck. 



Reference has been made to a peculiar system of oyster culture begun lately 

 in the mouth of the Suminouye River in Ariake Hay. The shores of the same 

 bay have extensive mud flats exposed more or less at low tide and here the cultiva- 

 tion of two other animals has gradually been developed, "agemaki" {Solecurtus 

 constricta), a shell somewhat resembling razor shells, and barnacles [Balanus sp.). 



The first <>f these ("agemaki," fig. 2. pi. xi) is dried and exported to China. The 

 trade began in ls75. and increased so rapidly that by L882-83 the supply was not equal 

 to the demand, and owing to the consequent overfishing the shells caught were 

 becoming smaller and smaller. To remedy this state of things, the Department of 

 Agriculture and Commerce established there an experiment station for the cultivation 

 of the shell, and one Mr. Negishi, belonging to the district, one year put in, for trial, 

 about L35 bushels of the shell in the tide flats, and found that these had increased by 

 the following year to 820 bushels, thus thoroughly demonstrating the practicability 

 of the culture. From this beginning the industry increased so rapidly that by 1896 

 in this part of the bay alone over 700 acres" were under cultivation and about 50,0011 

 bushels of seed shells were collected, and 112.S45 bushel- sold, fetching T'.»..".i".» yen. 

 The cultivation has since extended to other parts of Ariake Hay. and promises to 

 become more and more important. 



"The calculation of areas on the sett bottom in Japan is very rough and only approximate. As a 



general tiling it falls far short of the actualities. 



