268 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Over the southern part of the basin of the Gulf (Station 10058) 
BPS eT 
the plankton was qualitatively much the same — but quantitatively — f 
very different, for Calanus was not nearly so abundant in the haul 
from forty fathoms; the net, however, yielded many Euchaeta norve- 
gica, with few Calanus hyperboreus; and fully one half the catch con- 
sisted of Stephanomia bells and denuded stalks (p. 316); there were 
also more fish fry than were found nearer shore. 
At the Station on the northwest side of George’s Bank, a rather 
surprising discovery was made, namely that the surface water was full ~ 
of campanularian hydroids (Obelia) broken from their attachments, 
and many of them entirely regenerated. A similar phenomenon 
was noted on George’s Bank during the winter of 1912-1913 (1914b, 
p. 414). It is interesting faunistically as showing how the strong 
tides of the region, by keeping the detached hydroids afloat, mechani- 
cally introduce an exotic element into the plankton. So far as I can 
learn, nothing of the sort has been observed elsewhere, at least on so 
large a scale. The place of Calanus was taken by another copepod, 
Temora longrcornis, while the bulk of the deep haul consisted of — 
Sagittae (S. elegans). The net also yielded many young Cyanea, and: 
several caprellids, no doubt shaken loose from the hydroids. 
In the waters over Nantucket Shoals (Station 10059) Calanus was 
again the prevalent organism, with but few Sagittae; near the light- 
ship, however, (Station 10060), Sagittae about equalled Calanus in 
bulk; and this Station was also notable for swarms of young Euthe- 
misto (p. 281), of pteropods (Limacina balea, p. 304), and of the free 
medusae of Obelia. 
We saw fragments of Gulf weed on the surface south of Nantucket 
light-ship, and at Station 10061, over the eighty fathom curve, the 
influence of the Gulf Stream was made evident by the presence of 
Salpae, Phronima, and the amphipod Vibilia, though the bulk of the 
plankton still consisted of Calanus finmarchicus, with such other — 
boreal forms as Euchaeta norvegica, Euthemisto, Sagitta elegans, and 
Limacina balea. The plankton over the shelf south of Marthas Vine- 
yard and Block Island (Stations 10062 and 10063) consisted chiefly 
of swarms of young and old Euthemisto (p. 281), with smaller numbers 
of copepods (Calanus and Centropages, p. 287), Sagittae and an 
occasional Pleuwrobrachia pileus. And here for the first time large 
numbers of fish fry, a striking feature of the tows further south, were 
encountered. When the deep water outside the shelf south of Long 
Island (Station 10064) was reached the boreal plankton was replaced 
by a warm water assemblage, for while the 175 fathom haul still 
