148 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 
never in exact proportion to the duration. For example, doubling 
the duration will produce neither twice as many species nor twice the 
number of specimens. 
The plankton taken at stations 33 to 63, in the southern part of 
Bering Sea, among and north of the Aleutian Islands, furnishes in- 
teresting information. The copepod species recorded in these tows 
include many that are usually found considerably farther south. 
Species of Corycaeus, Farranula, Sapphirina, and Undinula are ordi- 
narily regarded as at least subtropical in distribution. Their pres- 
ence so far north suggests that the Japan Current, like the correspond- 
ing Gulf Stream in the Atlantic, transports plankton in the middle 
of summer far beyond its normal habitat. This has been recorded 
many times at Woods Hole, Mass., in connection with the Gulf Stream, 
and these copepod records testify to the same thing in connection 
with the Japan Current. 
Certain associations or companionships may be noted also among 
the different species. We naturally expect the various species of 
the same genus to be associated, since the environment favorable to 
one of them might be assumed to be favorable to all. The species 
of such genera as Candacia, Corycaeus, Hucalanus, Kuchirella, Labi- 
docera, Lucicutia, Oncaea, Pontellopsis, and Sapphirina, as well as 
many others, naturally swarm together in the plankton as a result 
of their relationship. Then there are also generic as well as specific 
companionships, genera that are so often found together in the same 
tow as to suggest a sort of Damon and Pythias friendship. Such 
genera as Undinula, Euchaeta, Metridia, and Acrocalanus are often 
found together, sometimes in large numbers. The surface tow at 
station 4009 contained a solid pint of copepods, made up entirely of 
Undinula vulgaris, Huchaeta marina, and Acrocalanus gracilis, and 
this grouping was repeated at a number of other stations. Why 
should not such an association suggest a closer relationship between 
these genera than is usually accorded them? Such a discussion of 
interrelations would afford a welcome relief from the harshness of 
stressing generic distinction. 
The five plankton lists of the Wilkes (Dana), Challenger (Brady), 
Siboga (A. Scott), Monaco (Sars, Rose), and Carnegie? (Wilson) 
expeditions listed on pages 148-145 were chosen for comparison with 
the results of the Albatross expeditions as here transcribed. They are 
the largest records covering in whole or in part the areas traversed 
by the Albatross. Hence such a comparison will give us at least a 
partial intimation of the changes that have taken place in the copepod 
content of the plankton during three-quarters of a century. Of 
7 [At the time Dr. Wilson discussed this list it was still in manuscript.—W. L. S.] 
