316 University of California Publications in Zoology [Vou.13 
orange-peel bucket dredge revealed only a few specimens of Mya. 
East of Point San Quentin the sample shows 12.26 per cent of lime 
at the surface, decreasing to about 10 per cent at a depth of 70.5 
centimeters. A large number of specimens of Ostrea lwrida were 
obtained at a near-by station. Again at stations D 5796 and D 5798 
the lime content is fairly high, but at those stations the water is nine- 
teen fathoms deep. The stony character of the bottom at station 
D 5702, which lies within the Golden Gate, would prevent dredging 
on a commercial seale. 
TABLE 5 
THE LIME ConTENT OF SOME OF THE TUBULAR BoTTom SAMPLES 
Nearest Depth Depth of 
“Albatross” dredging Percentage of sample water in 
stations station of lime in cm. fathoms 
D 5816 A D 5816 A ZONTOM” igs Fees 9 
H 5301 D 5798 15.33 46-56 10 
D 5796 D 5796 G58 9S eee 19 
H 5129 C D 5824 10.13 50.5-70.5 2 
H 5129 D D 5824 12.26 0-20 3.5 
D 5702 D 5702 QB en ne a seaeuetes 13 
H 5306 D 5834 10.38 0-10 10 
H 5309 D 5839 25.33 70-80 10 
H 5310 D 5836 21.75 91-108 5 
D 5783 D 5783 SGD) ayy Seer eee 2 
D 5847 A D 5847 A 24.86 125-136 8.5 
H 5312 D 5847 A 37.27 123.5-133.5 5 
_ Large quantities of Ostrea lurida were dredged off the Oakland 
Harbor Light at D 5832 and D 5833. They were also obtaimed abund- 
antly farther south at station D5835. Besides surface deposits, 
Sumner et al. (1914, pl. 6) show that a layer of shells from 50 to 80 
centimeters thick, extending from station H 5306 to H 5312, a distance 
of about sixteen miles, lies buried in the mud to a depth of about 50 
centimeters. It is this old layer that contributes to the lime content 
noted in table 5 at stations D5847 A, H 5129 C, H 5301, H 5309, 
H 5310, and H 5312. At all of these stations the water is less than 
ten fathoms deep, and the bottom is of a type of mud that might 
easily be dredged and then washed, leaving the concentrated shell. 
It is probable that the most extensive surface and subsurface deposits 
occur within a radius of five miles of Hunter’s. Point. A resurvey 
of those waters need not be expensive and might lead to the discovery 
of even greater deposits of shell than are now known. 
