322 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
of New York (Stations 10060, 10063, 10066). The only place where 4 
Pleurobrachia was abundant in the Gulf of Maine in 1913 was German _ 
Bank (Station 10095), where small specimens swarmed. The southern 7 
swarm of Pleurobrachia only once reached the surface (off Scotland+ — 
light-ship, July 12). Elsewhere it was limited to depths below about _ 
five fathoms; the water being from 15-30 fathoms deep over its area 
of abundance in this region. There were no Pleurobrachia in the Wy 
immediate surface layers where Salpae and Mnemiopsis often swarmed ; 
(p. 269). And the absence of Pleurobrachia in the immediate surface _ 
layers and on the surface can not be credited to the effect of sunlight, — 
because this-was as true of night as of day time stations. Most of the — 
Gulf of Maine captures were likewise in deep hauls; and there were 
none on the surface on German Bank, where a rich haul of Pleuro- ~ 
brachia was made at twenty fathoms. 
The shallowness of the water in the region where Pleurobrachia 
was most abundant, and the general rarity of the genus on the surface, 
make it easy to establish the salinity and temperature in which it was. 
living. The warmest water in which we can certainly establish its 
presence is 69° (Station 10066, surface), though some of the specimens 
from Stations 10074, 10077, and 10079, may have come from still 
warmer water. And south of New York in general the captures must 
have been in water warmer than 59°, that being the lowest tem- 
perature through which the nets fished. The swarm off New York — 
was in temperatures of 50° (ten fathoms) to 65° (surface near Scot- 
land light-ship). East of New York Pleurobrachia was usually living 
in water colder than 60°, with the minimum certainly as low as 48° _ 
(Station 10095), probably as cold as 48° (deep hauls in the Gull). — 
That is to say the genus covered practically the entire range of tem- 
perature encountered during the cruise, except the very warmest. It~ 
is not surprising to find Pleurobrachia at home in extremes as wide 
apart as this, because its range is known to be practically independent — 
of temperature. Nevertheless, there is some evidence that specimens 
of Pleurobrachia grow much larger in cold than in warm water, as 
Esterly (1914) has pointed out for the Pleurobrachias of the west 
coast of the United States. And our captures strengthen this view, 
for although the genus swarmed in water warmer than 58° off New 
York and further south, the specimens taken there were all small (less 
than 10mm. long). It was only in the cold water of the Gulf of Maine 
that we found large specimens; and work in previous years has shown 
that specimens upwards of 30 mm. long are common at the mouth 
of the Bay of Fundy, in summer, in temperatures of 50°-55°. 
