Contributions from the Biological Laboratory of the U. S. Fish Commission, 
Woods Hole, Massachusetts. 
THE FREE-SWIMMING COP 
OF THE WOODS HOLE REGION. 
By WILLIAM MORTON WHEELER, Ph. D., 
Professor of Zoology , University of Texas. 
An attempt to gain some knowledge of the pelagic copepod fauna of New England 
requires little justification, for even the most superficial student of marine zoology 
can not fail to be impressed by the vast number and variety of these little crustaceans 
and their mysterious appearance and disappearance at the surface of the sea. The 
closer observer will be attracted by the beautiful modifications of their structure, the 
interesting homologies of their parts — always a fascinating study in any group of 
arthropods — their peculiar sexual dimorphism, and their remarkable geographical and 
bathymetrical distribution. Then there is the great economic value of these creatures, 
which, as veritable “insects of the sea,” do inestimable service as scavengers and as 
the primitive and staple food supply of larger marine animals, such as fishes and 
cetaceans. Nevertheless, no group of animals has been more neglected by the zoologist, 
at least in America. This is probably attributable to a natural disinclination to take 
up the study of so large and intricate a subject — a disinclination which would have 
deterred the present writer from undertaking this study, had he not found in the 
recently published masterly monograph of Giesbreclit such an adequate treatmentof the 
free-swimming copepods that the identification and study of our species has become a 
pleasant and easy task. That I have followed him closely, without extensive reference to 
preceding writers — although I have consulted the monographs of Dana, Claus, Brady, 
and Thompson — is warranted by the undisputed superiority and the comprehensive 
character of his work. Still, Giesbreclit's work is only a magnificent beginning. 
During the few brief months that I have been able to devote to a study of our 
species I have gained the conviction that many new species, and even genera, occur in 
American waters. In the present paper I have described a few of the common species 
that are new, but a description of certain forms which seem to be types of new genera 
are reserved for closer study and subsequent publication. 
The materials for the following study were collected in the tow at the U. S. Fish 
Commission wharf, Woods Hole, Mass., in July and August 1899; Vineyard Sound, 
near Gay Head, Marthas Vineyard, July; Gulf Stream, 60 to 80 miles due south of 
Marthas Vineyard, July; and Plymouth Harbor, Massachusetts, August. The last 
two localities, one representing an arctic, the other a tropical fauna, are within a day’s 
journey of Woods Hole, and have been included in my study because they are easily 
accessible on the schooner Grampus and the steamer Fish Hawk and because many of 
the species of these regions will probably be found as stragglers at Woods Hole when 
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