1912] Esterly: Copepoda of the San Diego Region 255 
This paper is the second from the Marine Biological Station 
at La Jolla dealing with the distribution of plankton animals. 
The first is that by Michael (1911) which contains data for 
certain hauls that will be used by later writers. It is proposed, 
accordingly, to refer to that paper when it gives the data for 
any hauls used in this one. Michael and I made no attempts 
to use the same hauls, and for various reasons our lists are 
somewhat different. In a good many cases, however, we worked 
over the same collections, and where that is true I have stated 
where the data for those hauls may be found in Michael’s paper. 
On account of its earler appearance, Michael’s paper does not 
cover so many of the collections made by the station as does mine. 
I have followed the plan originated by Michael and arranged 
the data in four sections, the surface hauls being tabulated first, 
those with the horizontal closing nets second, then the hauls 
with vertical closing nets and last those with open vertical 
nets. Temperatures and salinities are given for surface hauls 
only, but one may gain some idea of the general relation between 
depth, temperature and salinity from McEwen (1910). 
The various nets used in collecting are referred to in the 
tables by letters, as follows: 
A. Surface net of 000 XX mesh silk bolting cloth; the orifice of 
the net being 97.5 em. in diameter. 
B. The Kofoid horizontal closing net, the material the same as above, 
the orifice of the net being 37.5 em. in diameter. 
C. The ‘‘small’’ Nansen net, of 1 XX silk bolting cloth, the orifice 
about 45 em. in diameter. 
D. The ‘‘large’’ Nansen, of the same mesh as net C, but the 
orifice 109.5 em. in diameter. 
E. A Nansen net of 0 XX bolting cloth, the orifice of the net 
62.5 em. in diameter. 
F. The ‘‘000’’ Nansen, of 000 XX bolting cloth and 62.5 em. 
across the mouth, 
It should be noted here that in Michael’s paper there has 
been a shght error in not distinguishing between nets C and D 
of the list above. He designates both nets of No. 1 silk as net C 
in his list, when really some of the hauls in his Tables 30 and 32 
were made with the large Nansen net (D above). Since refer- 
ence is made from this paper to Michael’s, the following in his 
