PLANKTON OP THE GULF OF MAINE 237 
32 to 33 per mille are an effective bar to its wanderings, and its distribution in the 
Gulf of Maine is consistent with this. 
Economic importance . — E. norvegica has been considered as of comparatively little 
economic importance in the northeastern Atlantic because of the considerable depth 
of its habitat. But it occurs regularly within reach of at least one of the important 
plankton-eating fishes in the Gulf of Maine, for Willey (1921) found the stomach of 
an American pollock (. PoTlachius virens ) densely packed with a mass of Euchasta and 
euphausiid remnants in about equal amounts, the percentages of different copepods 
which he tabulates — 84 per cent Euchseta, 3 per cent Galanus iinmarchicus, 2 per 
cent C. hyperboreus, and 1 per cent Metridia longa — suggesting that the fish had 
voluntarily selected the Euchsetae in preference to the smaller C. finmarchicus , which 
was probably far the more plentiful of the two. Another pollock opened by him 
had also eaten Euchreta. To what extent mackerel and the several species of her- 
ring feed upon it in the gulf is not known, but it is likely to be an important article 
in their diet when it rises toward the surface. 
Euclieeta spinosa Giesbreclit 
This species, known from localities in the North Atlantic, Mediterranean, 
Indian Ocean, and Pacific (Giesbreclit, 1892; van Breemen, 1908; Thompson and 
Scott, 1903; Esterly, 1905), has been reported from surface collections off Nausett 
Beach, Cape Cod, and off the northern extremity of the cape by Sharpe (1911, 
p. 410), but it has not appeared in any of the more recent towings in the gulf or in 
Canadian Atlantic waters. 
Eucbeirella rostrata (Claus) 
This is an oceanic species, widespread in the temperate Atlantic (Cleve, 1900; 
T. Scott, 1911) and common on the Pacific coast of the United States at San Diego, 
Calif. (Esterly, 1905 and 1911). It has been recorded at several stations along and 
outside of the continental edge off Chesapeake and Delaware Bays and off New 
York (Bigelow, 1915, p. 296; 1922, p. 147), abreast of Georges Bank (stations 10218 
and 10219), and thence eastward and northward along the slope of the Nova Scotian 
shelf and in the Laurentian channel (Willey, 1919, p. 189, fig. 9). Although this cope- 
pod is not typically tropical, it enters the Gulf of Maine as a visitor from the mid- 
depths along the inner edge of the “Gulf Stream,” and its locality records, like 
those for other planktonic organisms of that category, are localized in the eastern 
side of the gulf and around its periphery (fig. 71). The station records number 13, 
all but 4 of them being for July and August — 2 for May, 1 for June, and 1 for 
September. Evidently the species is most apt to enter the gulf during the warm 
months, and apparently it does not do so at all in the low temperatures of late 
autumn, winter, and early spring. 
All records of the species off the east coast of America have been from depths of 
50 meters or deeper, and the Gulf of Maine records are all based on occasional 
specimens. 
