100 
BULLETIN OF THE BUBEAU OF FISHERIES 
provided an ideal pasture for the Atlantic right whale, of which it once fully availed 
itself, as early records show, but not for the finback, for which the bay is a desert 
except when herring or other fish are schooling there or during the brief local swarm- 
ings of euphausiids. It is common knowledge among fishermen that finbacks 
seldom appear in any numbers anywhere in the gulf except when in pursuit of fish. 
It is also probable that the volumetric preponderance of copepods over euphausiids 
in most parts of the gulf explains the comparative rarity there of the shrimp-eating 
blue whale with its very coarse whalebone. 
Before leaving this subject I should emphasize that the large, easily recog- 
nized, pelagic amphipod Euthemisto, locally and temporarily so abundant, has 
never been recognized in the stomachs of any of the whalebone whales. Is it not 
eaten? And if not, why not? 
It is probable that copepods are the main dependence of the basking shark 
( Cetorhinus maximus), whose gillrakers perform the same service in filtering its 
crustacean food from the water taken into the mouth as do the baleen plates of the 
whalebone whales. I need merely point out that the alimentary canal of a speci- 
men taken at West Hampton Beach, Long Island, on June 29, 1915, contained a 
large quantity of minute Crustacea, “whose reddish bodies lent color to the entire 
mass” (Iiussakof, 1915, p. 26). 
When we turn to the dependence of the smaller fishes on crustacean plankton, 
we are confronted by a published record so embarrassing for its wealth (mostly, 
however, based on experiences in European seas) that I shall lay only a few of the 
more typical examples before the reader, and those most applicable to the Gulf of 
Maine. 
The unicellular plants have been described repeatedly in zoological literature as 
the chief food supply of the youngest larval fishes, and a long list of diatom and peri- 
dinean species has, at one time or another, been recorded as having been eaten by 
them; but recent studies of the stomach contents of large series of various common 
fishes in the English Channel (Lebour, 1919, 1920, 1924) have proved that although 
many fish do take more or less diatoms, peridinians, etc., few depend on these uni- 
cellular forms to the extent that has been generally supposed, even during their 
earliest larval stage (cf. also Hjort, 1914, p. 205), but begin to take larval copepods 
and other microscopic animals by the time the yolk sac is absorbed, if not sooner. 
However, Lebour found the young European flounder (Pleuronectes flesus) subsisting 
chiefly on the green flagellate genus Phseocystis up to the time of its metamorphosis, 
with other flatfish taking a considerable proportion of peridinians and diatoms, and 
this proved true of young herring less than 10 millimeters long, which also take Halo- 
sphgera. 
Outside of the littoral zone, where the mummichogs ( Fundulus heteroclitus) 
consume diatoms as well as other small organisms indiscriminately, the menhaden 
is the only important Gulf of Maine fish that continues throughout life to subsist 
chiefly on diatoms and peridinians, with the most minute of Crustacea and other 
animals. These it is enabled to sift out of the water by its fine branchial sieve, as 
Peck (1894) long ago described. 47 
<7 On the feeding habits of the menhaden see also Bigelow and Welsh, 1925, p. 123. 
