8 University of California Publications in Zoology [ Vou. 14 
bolting-cloth was employed, attached to a rine 4 feet in diameter, 
together with two smaller nets, of no. 12 and no. 20! bolting-cloth 
respectively, and having an aperture of about 14 inches. The contents 
of the three nets were preserved separately, and kept distinet by those 
engaged in studying the collections. 
The tow-net hauls were horizontal ones of rather indefinite dura- 
tion and depth. When the current was sufficiently strong, the nets 
were allowed to swing freely in the latter during the ten-minute 
period in which the vessel was at anchor for the hydrographic obser- 
vations. When the tidal current was too weak to carry the nets into 
a horizontal position the vessel steamed slowly for five or ten minutes 
after lifting anchor, and the plankton haul was then made. The nets 
were lowered to a point some distance above the bottom, an iron 
weight (138 pounds) being attached to the end of the cable. Exact 
control of depth was unfortunately impossible, and care was necessary 
in order to prevent the rim of the larger net from scraping the bottom 
and scooping up large quantities of mud. Vertical hauls were found 
to be impracticable, owing to the force of the tidal currents. 
In such shoal waters as those of San Francisco Bay, and particu- 
larly amid such swift currents, it does not seem likely that the vertical 
distribution of plankton is commonly of much significance. At any 
rate, no observations have been made by us to test this point. 
In addition to the taking of plankton at the regular hydrographic 
stations, tow-net hauls with the three nets referred to have been made 
at weekly intervals in the vicinity of Sausalito, throughout a consid- 
erable number of months, at various seasons of the year. 
The animal and plant species from each of these various stations 
have in a large degree been sorted out and referred to appropriate 
specialists. Bottom samples were likewise saved from most of the 
dredging stations and from many of the hydrographic stations, while 
water samples, both from surface and bottom, were preserved at all of 
the latter. 
For the use of those engaged in a study of one or another group 
of organisms, blue-print charts were early prepared, indicating the 
position of the various stations so far occupied in San Francisco Bay, 
and mineograph sheets were likewise distributed, giving such notes 
as to depth, character of bottom, salinity, temperature, ete., as had 
been recorded for each. These data, in a revised form, appear in the 
appendices to the present report. A special chart (pls. 3 and 4) for 
1 This is the cloth generally known to planktologists as “No. 20.’’? Lohmann 
(1911) states that this number was changed by the manufacturers in 1907 to 
GEIS Pa? 
