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 siphonophores 
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, Euthemisto compressa, 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 bispinosa, 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 
\Norwegian Seas, because the quantitative nets used, speed of hauling, 
‘ete., have not been alike; and because the coefficient of filtration has 
ot 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 
jist for the North Sea (Apstein, 1906; Johnstone, 1908). The bulk 
bf plankton below each square meter of surface of the Gulf of Maine, 
jn the summers of 1912 (1914a) and 1913, ranged from 10 ce. to 250 ce. ; 
‘in 1913 the average for the whole Gulf was about 100 ce. Much 
\reater amounts than this were found in the northeastern part of the 
North Sea by Apstein, who records volumes of 96-952 cc.; below each 
‘quare meter of surface in August, 1903; with an average of about 
40 cc. for thirteen hauls. And even admitting all the objections 
yhich can be urged to volume as a measure of plankton (Steuer, 1910), 
) great a difference as this can only mean that there was a greater 
—ulk of plankton in the North Sea in 1903 than in the Gulf of Maine in 
12 and 1913. And the discrepancy between the two regions is even 
‘eater, if the comparison be extended to the amounts of plankton 
t cubic meter, for the largest amounts in the Gulf (p. 326) is only 
pout one tenth of Apstein’s largest record (27.2 cc.) for the North 
or 
