BIGELOW: COAST WATER EXPLORATION OF 1913. 341 



hyperiid amphipods known from the Gulf of Maine are more or less 

 regularly recorded (Tesch, 1911). In fact, all the species without 

 exception which are listed as particularly characteristic of our Gulf 

 (p. 273) meet one another in this region, most of them being regularly 

 recorded in the plankton lists of the International Committee for the ex- 

 ploration of the sea. And the various Salpae, southern siphonophorei- 

 and other warm water species make their appearance in summer 

 (Damas, 1909, p. 107), just as they do in smaller numbers in the Gulf 

 of Maine. But the relative importance of the various species is not 

 quite alike, for example, Euthcmisto cornpressa, one of the most con- 

 stant members of the plankton of the Gulf of Maine, especially in 

 summer, is usually rare (Tesch, 1911) in European waters. Its place 

 is taken there by Parathemisto oblivia, which occurs in at least 50%, 

 usually 75% of the hauls in the Norwegian Sea and the northern part 

 of the North Sea; but P. oblivia is so rare in the Gulf that I have 

 detected only two specimens among the thousands of Euthemisto 

 which have passed under my notice (p. 335). Euthemisto hispinosa, on 

 the other hand, is far more abundant on the western than the eastern 

 side of the North Atlantic. 



It is not yet possible to state the quantitative relationship which 

 the plankton of the Gulf of Maine bears to that of the North and 

 Norwegian Seas, because the quantitative nets used, speed of hauling, 

 etc., have not been alike; and because the coefficient of filtration has 

 not been determined for our nets. But this phase of plankton study 

 is so important in its practical bearing on the food supply for fishes 

 that it is worth while to compare our results briefly with Apstein's 

 list for the North Sea (Apstein, 1906; Johnstone, 1908). The bulk 

 of plankton below each square meter of surface of the Gulf of Maine, 

 in the summers of 1912 (1914a) and 1913, ranged from 10 cc. to 250 cc; 

 in 1913 the average for the whole Gulf was about 100 cc. Much 

 greater amounts than this were found in the northeastern part of the 

 North Sea by Apstein, who records volumes of 96-952 cc. ; below each 

 square meter of surface in August, 1903; with an average of about 

 340 cc. for thirteen hauls. And even admitting all the objections 

 which can be urged to volume as a measure of plankton (Steuer, 1910), 

 so great a difference as this can only mean that there was a greater 

 bulk of plankton in the North Sea in 1903 than in the Gulf of Maine in 

 1912 and 1913. And the discrepancy between the two regions is even 

 greater, if the comparison be extended to the amounts of plankton 

 per cubic meter, for the largest amounts in the Gulf (p. 326) is only 

 about one tenth of Apstein's largest record (27.2 cc.) for the North 



