99 BULLETIN OF THE BUREAU OF FISHERIES 
carried on by Dr. H. B. Bigelow, are published in a series of bulletins from the 
Museum of Comparative Zoology at Cambridge, Mass., and a more complete 
account of these investigations and explorations is now in process of publication. 
It has long been known that Woods Hole occupies a unique position on the 
Atlantic coast. It is the northern limit of many southern forms and the southern 
limit of many northern forms. Oceanic animals, also, are often carried into this 
pocket on the coast by the southerly winds and strong tides that prevail in the 
summer months. For that reason Woods Hole was selected as an ideal location for 
the study of plankton and the interrelationships of the various pelagic faunas. 
Under “‘plankton’’ I have included all animals occurring in surface collections, 
whether free-swimming or carried by currents. Such a broad definition includes a 
great many benthonic forms carried from their natural habitat by storms or high 
winds, but in a littoral region one can not always decide accurately which species 
have been accidentally carried to the surface and which are free-swimming. 
The present paper is the result of a continuous investigation of the plankton 
in Great Harbor, Woods Hole, Mass., covering a period of two years. The purpose 
was to make an exhaustive qualitative study of the plankton of this region, the 
seasonal distribution of the various species, their interrelationships, and the general 
factors governing their distribution. 
The investigation consisted of three parts: (1) An examination of plankton 
samples taken daily during the years 1899 and 1900 in Great Harbor by the late 
Vinal N. Edwards, collector for the United States Fish Commission; (2) a survey of 
all records of surface collections of previous years; and (3) examination of living 
material taken daily in surface collections in Great Harbor, observations on tem- 
perature, salinity, and other factors governing the seasonal distribution of the 
plankton, and a survey of the general geography of the region as a factor affecting 
plankton distribution. 
The first part of the investigation occupied the entire time of the author during 
the year 1921-22 and was carried on in the biological laboratory at Brown Uni- 
versity. Many of the fragile animals had become disintegrated during the 22 years 
in which the material had remained untouched, and the preservatives in some of 
the samples had evaporated. Over 200 vials remained intact, however, and offered 
ample material for study. 
The second part of the work involved much time and proved to be a very 
tedious task. The results, however, were very important, as they covered the 
daily records of surface collections extending over a period of 15 years—1893 to 
1907, inclusive. ‘The larval fish and celenterates taken during this time had been 
carefully identified by Vinal N. Edwards. Diatoms, copepods, amphipods, annelids, 
and other planktonic forms were recorded as groups, the relative abundance for 
each day bemg carefully noted. Complete records of the weather, wind, and 
temperature for most of this period were available and proved indispensable in 
explaining peculiarities in the seasonal distribution of many species. This part of 
the work was done by Marie D. P. Fish, who aided me in the study of the larval 
fish also. 
The final part of the work was carried on from June 22, 1922, until December 
31, 1923, at the laboratory of the United States Bureau of Fisheries at Woods Hole, 
