PLANKTON OF THE GULF OF MAINE 365 
Eastport, one specimen, summer of 1885 (Fewkes, 1888, p. 235); and Western Basin, 
March 24, 1920, 200-0 meters, Albatross station 20087. 
Dactylometra quinquecirrha, a southern species, is fairly common as far east and 
north as the Woods Hole region, but has never been taken past Cape Cod. 
The bathypelagic Periphylla hyacinthina has been credited to Georges Bank. 7 
Actually, however, the specimens in question were taken off the southeast slope of 
the latter well out beyond the 500-meter contour (Smith and Harger, 1874, p. 52, 
as “ Charybdea hyacinthina”). Pelagia cyanella and the large tropical rhizostome 
Stomolophus meleagris have been reported just outside the 100-meter contour south 
of Marthas Vineyard (Fewkes, 1886, and Hargitt, 1905a), and the cruises of the 
Albatross from 1883 to 1885 yielded a considerable list of tropical and bathypelagic 
scyphomedusae (including Periphylla) outside the edge of the continent abreast of 
the Gulf of Maine (Smith and Harger, 1874; Verrill, 1885; Fewkes, 1886). How- 
ever, except as just noted, none of these have ever been taken inside the 500-meter 
contour off the offshore banks of the gulf or within the latter. 8 
Ctenophores 
PleuLrobrachia pileus (Fabricius) 
From the economic standpoint the ctenophore Pleurobrachia pileus 9 is the most 
important pelagic coelenterate inhabiting the Gulf of Maine, for not only is it ex- 
tremely voracious and locally abundant beyond all computation, but it is present 
there throughout the year, not for only a brief season annually, as are Aurelia 
(p. 362) and Cyanea (p. 357). 
The abundance in which Pleurobrachia appears in Massachusetts Bay and 
elsewhere along the New England coasts in summer and early autumn has often 
been referi’ed to in literature, but practically nothing was known of its occurrence 
in the gulf at any other season until the recent systematic exploration was under- 
taken. During March and April (which is a natural starting point in the seasonal 
history of any planktonic animal, being the time when vernal warming makes itself 
felt) we have found Pleurobrachia occurring very generally all around the periphery 
of the gulf from Cape Cod to Cape Sable (fig. 101), but so closely confined to shoal 
water that we took it only twice outside the 100-meter contour in the inner parts 
of the gulf in 1920 and not at all in the basin of the gulf except for the extreme north- 
eastern corner. Nor did we find it on Georges Bank at any of our February, March, 
or April stations, though it was plentiful on Browns Bank on March 13 (station 20072) 
and again on April 16 (station 20106). 
Our experience in 1915 suggested that Pleurobrachia remains confined to the 
shoal periphery of the gulf until well into May, if not later, as I have previously 
noted (Bigelow, 1917, p. 304), but we found it in abundance on the southwestern 
part of Georges Bank and less plentifully off the seaward slope of the latter on the 
17th of that month in 1920 (stations 20128 and 20129), where there had been none 
7 1 fell into this error myself (Bigelow, 1914b, p. 27). 
> See also page 67 for a list of bathypelagic medusse from our outermost station off Shelbourne, Nova Scotia, Mar. 19, 1920 
(station 20077), and page 54 for tropical ccelenterates at the outer station off Georges Bank, July 21, 1914 (station 10218). 
* For a description, with beautiful figures of the adult, see L. Agassiz, 1849. Mayer (1912) gives a more recent account. 
