UNIVERSITY OF CALIFORNIA PUBLICATIONS 
ZOOLOGY 
Vol. 2, No. 4, pp. 113-233, Figs. 1-62. October 14, 1905 
CONTRIBUTIONS FROM THE LABORATORY 
OF THE 
MARINE BIOLOGICAL ASSOCIATION OF SAN DIEGO. 
IV. 
THE PELAGIC COPEPODA OF THE 
SAN DIEGO REGION. 
BY 
C. O. ESTERLY. 
The present paper is the result of a study of the pelagic Cope- 
poda collected in the San Diego region during one month of the 
summer of 1903, nearly two months of 1904, and during Decem- 
ber and January, 1903. Likewise, there have also been examined 
a few collections taken during the fall of 1904. Such time as 
has been spent on the subject serves to convince the writer that 
a good deal of further study is necessary, and that, taking the 
field as a whole, this report is incomplete. Such forms as are 
deseribed here seem well established. Without doubt there are 
others which are new, but for lack of proper material they are 
not now dealt with. 
The work was commenced at the San Diego Marine Labora- 
tory connected with the University of California, and completed 
at Harvard University. It is a pleasure to express my apprecia- 
tion of the helpful suggestions and advice of Professor W. E. 
Ritter of the University of California, and Professor E. L. Mark 
of Harvard University. 
In the body of a free-swimming Copepod two regions are 
readily distinguishable, a cephalothorax and an abdomen. In 
the first suborder, Gymnoplea, the cephalothorax consists of the 
head and five thoracic segments, though the head is often fused 
with the first thoracic segment, and the fourth with the fifth. 
In the second suborder, Podoplea, the last thoracic segment is 
drawn into the abdominal portion; this, then, loosely speaking, 
contains one thoracic segment. 
