352 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
upon the piles of an old narrow-gauge railroad trestle, across a slough, 
near Dumbarton Point, and that the men of his party frequently found 
many upon banks composed of shells of the native species, near where 
the pipes of the company cross the bay. a ee 
Mr. H. D. Dunn has recently reported, through the press, the discov- 
ery of a full-grown eastern oyster near Mile Rock, in the Golden Gate. 
It is possible that during the long time eastern oysters have been 
kept in the bay they have become in a measure acclimated, and that 
there is a constantly increasing tendency to propagate—that is, the 
progeny of oysters grown here become hardier with each generation | 
and better adapted to the colder but more equable waters. 
During my latest examinations of the bay (May and June, 1891) 
eastern oysters, very large and old, were found in the following places 
near the sites of former oyster beds: Several adhering to the piles of 
the narrow-gauge railroad trestle across San Léattizo Bayy atone 
the rocks at the extreme north point of Sheep or brooks Island, near 
low-water mark; a few upon the rocks at Point San Pedro (at bate ance 
“to San Pablo Bay). Those from San Leandro Bay doubtless originated 
asspat from the oyster bed near the entrance to that bay, at the end of the 
bay northwest from the island. Those from Sheep Island had merely 
drifted as_young across the half mile of distance from the old beds 
near Ellis Landing, while the San Pedro oysters originated upon the 
beds pepen Marin Island and Point San Quentin, a couple of miles 
distant. ————_ 
Mr. H. D. Dunn informed me that wild eastern oysters had been 
reported to him from some other place near Point San Pedro, but I did 
not discover them, being without a pilot. These finds are very inter- 
esting, as showing not only the breeding of the oyster in various parts 
_ of the bay, but that the species began breeding several years ago when 
oysters were laid out in those northern parts of the bay. At Point San 
Pedro oysters are directly exposed to the influences of the Sacra- 
mento River. But the largest and most important tract of oyster 
propagation is in the region of the natural shellbanks of native oys- | 
ters along the east side of the bay, beginning at Bay Farm Island and 
extending well southward and off into deep water. Here wild eastern 
oysters may be found during the low tides that expose the outer por- 
tions of the shellbanks. At this place they are numerous, and when 
the tides are sufficiently low it is possible to gather them by the score, 
ranging in size from yearlings to those several years old. This deposit 
is at least 4 miles removed from the nearest site of a former oyster 
bedding-ground, and there is no doubt about the oysters upon the 
whole tract being of volunteer growth. A channel several feet wide 
separates this tract from the old bed on the north, while it is nearly 10 
miles to the nearest beds on the south. 
Examination of two or three hundred oysters gathered in this region 
Shows the fixing surface for the spat to have been the shells of the 
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