92 THE HAMILTON ASSUCIATION. 
fail in a very few years, and this prediction has since been accom- 
plished. Since the decline, fresh diving grounds have been 
discovered in North Australia and the Philippines. It is said an 
English company, of which Mr. Streeter, of London, is a mem- 
ber, employs quite a number of vessels in the business, and the 
mother-of-pearl shells are of more value than the gems they 
contain. A United States daily, the St. Zowzs Democraz, mention 
the company, in one year of the Australian fishery, netted (at 
$100.00 a ton) $400,000 for the former, and the value of the 
latter was estimated at about a third of this amount. Perhaps 
these figures are unreliable, and the syndicate may not care to 
publish the true state of its affairs. The pearls of the ‘‘ Sudus”’ 
are said to be remarkable for their beautiful iridescence. 
THE PINNA. 
This thin wedge-shaped shell is remarkable for the beauti- 
ful silken bysus by which it attaches itself to the sea-bottom 
rocks, etc. While Woodward places it with the above family 
group, Ward holds it entitled to family distinction as Pinnide, 
stating, ‘‘ Unlike the Avzcudidw, the species of this genus have 
been steadily increasing in numbers since Geological times. ” 
We may think this circumstance insufficient for the change, 
however. The silken byssus is made into gloves, and used for 
various ornamental purposes by the natives of Italy and the 
countries to the north of the Mediterranean sea. The Aviculide 
are well represented from the lower Silurians upwards. The 
range is world-wide, and several are found fossilized in this 
neighborhood in good preservation. Among them we enum- 
erate ‘‘ Ambonychias,”’ ‘‘Posidonomyas, ’’ ‘‘ Posidonia.”” We 
have reason to believe the Pectens, or Scallops, which made 
their appearance in a more recent time, derived their descent 
from the Aviculide. McCoy named a Conchifer from the Car- 
boniferous which bore as close a resemblance to the one as to 
the other Aviculopecten, and I have found Conrad in New York 
State calls a specimen he discovered there ‘‘ Avicula_pec- 
teniformis, ’ which amounts to ‘‘like a Pecten.” The Scallop 
fishery of Ireland is of considerable importance. They are said 
