THE HYDROIDS OF THE WOODS HOLE REGION. 
By C. C. NUTTING, 
Professor of Zoology , University of Iowa. 
INTRODUCTORY NOTE. 
The limits of the “Woods Hole region,” in the sense here used, may be roughly 
defined as follows: Starting with the point of Cape Cod as the northern and eastern 
limits, following the New England coast to New London, Conn.; thence southward to 
the end of Long Island; thence southeast to the edge of the Gulf Stream, which is 
followed until off Cape Cod. These limits embrace, roughly, the area that can be 
covered by one-day excursions by steamer from the U. S. Fish Commission station 
at Woods Hole, Massachusetts. 
It is the purpose of this pamphlet to furnish collectors and workers in this 
region with a practical and concise means of identifying the species of hydroids known 
to occur within the area above described. There are a number of other species that 
almost certainly occur within the Woods Hole region, but, with one or two exceptions 
involving species of unusual interest, these will be omitted. 
Most of the material studied in connection with this work was secured by the 
author during three summers spent at the U. S. Fish Commission laboratory at 
Woods Hole and a month at the laboratory of Ur. Alexander Agassiz, at Newport. 
The number of species listed indicates a fairly rich hydroid fauna in the region, 
the general relation being with the Arctic or rather Holarctic fauna, which explains 
the large percentage of British forms represented on our Atlantic coasts. 
The illustrations are from sketches originally made by the author to illustrate a 
monograph of the North American hydroids, in course of publication by the United 
States National Museum. Permission was given by the authorities of that institution 
to have ink tracings made from these sketches, which have been reduced in size and 
used in the present work. 
In order to secure the brevity necessary for the treatment of the subject in the 
form of a practical guide to identification, it has been necessary to omit all discussion 
regarding synonymy. In naming genera and species a conservative course has been 
followed, although the names in some cases have been changed in what will doubtless 
appear to be an arbitrary manner. The reasons for these changes are in most cases 
briefly indicated, but the explanations are not so full as would be deemed requisite in 
a work of more strictly technical nature. 
Under the head of “ distribution ” localities are given where the species have 
been found in the Woods Hole region. 
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