34 
BULLETIN OF THE UNITED STATES FISH COMMISSION 
careless handling will destroy great numbers of the delicate shells; hasty packing of 
the shibi on the scows, whereby the branches are allowed to rub together, is another 
palpable source of loss; drying, direct sunlight, changes of temperature, are all 
deadly, and, above all, severe thunderstorms — the latter, according to my informant, 
causing death by fear. I suspect, however, in the last regard, that a fresh, cold 
shower bath is more apt to be a moving cause, although I was assured that the scows 
are covered with the ever-present Japanese oiled paper to guard against such a 
contingency. 
(b) Rearing the young oysters . — The shibi, covered with young spat, are now 
arranged in toya-ba, like those of Kusatsu, but closer in arrangement and usually 
of many varieties. Here they remain from one to two and a half years. In the 
Fjq. 20. — Diagram of living ground of two to three year old oysters. The spots represent oysters and the dark 
lines are rows of shibi placed so as to provide shelters against currents or storms. The arrow denotes direc- 
tion of strongest current. 
case of the older and rearranged toya a long, mound -like type is commoner than 
the circular ones described above. As a rule the toya are covered with water save 
at lowest tides. 
(c) Later rearing ; Maturing . — The living inclosures in deeper water, ike-ba, 
correspond to those of Kusatsu. They contain the oysters which have been separ- 
ated or are readily separated from the brush of the toya. A similar process prevails 
of raking the oysters roughly, and I was shown some shells of the older oysters 
from this region which were of very regular shape. At. favorable tides, further- 
more, the oyster beds are cleaned and the boring whelks — Purpura clavigera Kaster 
