414 bulletin: museum of comparative zoology. 



Finally, a phenomenon of some interest is the apparent absence of 

 Meganydiphanes norvegica from Massachusetts Bay at all seasons. 

 There seems to be nothing in temperature or salinity to bar it from 

 the waters of the Bay, for in summer, at some depth, the Bay closely 

 reproduces the combination of temperature and salinity in which we 

 found it swarming in Eastport Bay in August (salinity about 32.4% p to 

 32.6%o, temperature 52°) ; and in winter the Bay is very little colder 

 than the northern part of the North Sea, where Meganyctiphanes is 

 common at that season. Its absence or rarity in the Bay is perhaps 

 analogous to its absence in the southern part of the North Sea, where, 

 as Kramp points out, both salinity and temperature would allow its 

 existence. His explanation is that it is prevented from spreading 

 southward in the North Sea by the shallow water, Meganyctiphanes 

 being, according to his view, chiefly an inhabitant of the deeper water 

 layers. But it can hardly be shallow water which bars it from Massa- 

 chusetts Bay because many of our records for the species were from 

 hauls no deeper than the deeper parts of the Bay, and because it was 

 found in swarms on the surface at Eastport, in water of almost pre- 

 cisely the same temperature and salinity as the surface water off Cape 

 Ann in November. Food supply, not hydrographic conditions, may 

 be the factor which determines the local occurrence of Meganycti- 

 phanes in the Gulf. 



Plankton from Georges Bank. 



The data for the season is limited to the few hauls made by Mr. 

 Douthart during two trips, April 14th and 26th-27th, which, being 

 taken at the surface with a small net, cannot be expected to give so 

 complete a survey of the plankton as the work carried on in Massa- 

 chusetts Bay. There must have been a fairly abundant macroplank- 

 ton on his first visit, for the samples contained a considerable 

 number of copepods, chiefly Calanus finmarchicus and Temora longi- 

 cornis in the proportion of about 5-2; Sagitta elegans, and many 

 specimens of the small Anthomedusa Hyhocodon prolifer, with a few 

 young Staurophora mertensii. The list also includes occasional 

 specimens of Oikopleura dioica and Tomopteris helgolandica, besides 

 many Arachnactis larvae; but the most interesting find is a large 

 number of small colonies of two species of campanularian hydroids 

 which were evidently living under pelagic conditions at the time, 

 because the stems present no broken ends, but are growing actively 



