PLANKTON OF THE GULF OF MAINE 
355 
Only eight hauls (whether with the open or closing nets) from deeper than 160 meters 
have yielded Aglantha. Evidently, then, this medusa lives chiefly in the upper 
strata of water in the Gulf of Maine, just as it does in the North Sea region (Kramp, 
1913) and for that matter over the North Atlantic as a whole, though not on the 
surface. The frequency of captures in hauls made between 50 and 150 meters (a depth 
range which included about 40 per cent of all Gulf of Maine records for Aglantha) 
points to this stratum as its chief center of abundance. The greatest depth from 
which I can definitely establish the presence of Aglantha within the gulf is ISO to 
140 meters (closing net, off Mount Desert Rock, March 3, 1920, station 20055). The 
only specimen we have taken in a tow from deeper than 200 meters (240-0 meters, 
station 20049, western basin, February 23, 1920) may have been picked up by the open 
net on its journey down or up; nor is it any more certain that the few Aglanthas 
which we have collected along the continental slope ostensibly from 400-0 and 500-0 
meters (e. g., station 20077, March 19, 1920), but in open nets, actually came from 
so great a depth. 
Aglantha is seldom abundant in the Gulf of Maine; in fact, most of the records 
obtained by the Grampus, Albatross , and Halcyon (now amounting to the respectable 
total just mentioned) are for single or occasional specimens. Only five times have we 
taken it in large numbers — that is, near Lurcher Shoal, May 10, 1915; near Glouces- 
ter, July 19, 1916 (station 10340); in Provincetown Harbor the next day (station 
10243); off Gloucester, October 31 of that same year (station 10399); and on the 
southeast part of Georges Bank, March 12, 1920 (station 20069). 
Aglantha is present in the gulf throughout the year, taken there during every 
month except October, when we have done little towing; nor is there anything in our 
records to suggest that it is notably more abundant at one season than another, for 
the rich hauls just mentioned were made in spring (March and May), summer 
(July), and autumn (October). It is probable, however, that a more intensive 
study of the local occurrence of this medusa in the gulf would show that its numbers 
there do wax and wane with the succession of the seasons. At Woods Hole it occurs 
most often in spring (March to May, according to Hargitt, 1905). 
Although the distribution of Aglantha in the Gulf of Maine is more consistent 
with an extralimital source of supply than with widespread local production such as 
maintains the stocks of Calanus, Thysanoessa inermis, Sagitta elegans, or even Euchse ta 
in the gulf, the fact that very young specimens as well as adults have repeatedly 
been taken there not only during our recent cruises but half a century ago (A. Agas- 
siz, 1865) is evidence enough that it reproduces itself to some extent. Occasionally 
a local wave of production must take place to produce such an abundance of the 
young medusae as we found off Cape Ann on October 31, 1916 (Bigelow, 1922, 
p. 136; station 10399). 
Aglantha, large or small, is usually so scarce anywhere in the gulf that such 
events must be unusual. Additional information on this point would be very welcome, 
for it is not possible to appraise the faunal significance of the occasional swarmings 
of Aglantha as indices to influxes of northern water into the Gulf of Maine without 
knowing how regularly the stock of this species existing there is replenished by local 
breeding. 
