BIGELOW: EXPLORATIONS IN THE GULF OF MAINE. 117 



Station A 6 miles off Cape Porpoise August 18 8 fathoms. 



Capt. John McFarland. 

 Station B 8 miles E. of Chatham September surface. 



Capt. John McFarland. 

 Station C 12 miles S. E. of Chatham September 10 fathoms. 



Capt. John McFarland. 



Distribution of the more important plankton species. 



Among the objects of the exploration of the Gulf is the correlation 

 of the distribution, seasonal and geographic, of the more important 

 members of the plankton with the physical characters of the waters 

 in which they live ; and the determination of the factors which govern 

 their times of reproduction, movement, and abundance. Obviously 

 the summer work in 1912 is only the first attack on the problem; but 

 the data acquired is valuable because salinity and temperature are 

 known for the various captures, and can be used as the basin of future 

 work. In the following notes, the occurrence of some of the more 

 important animals is summarized, without any reference to earlier 

 records for the region. 



Calanus finmarchicus. — As pointed out, (p. 99) this copepod was 

 taken at every station, including the harbors of Gloucester, Kittery, 

 and Portland; and it greatly predominated over all others at most 

 of the off-shore stations. The exceptions, as noted above (p. 105), 

 and in the table (p. 115), were the surface hauls at Stations 41 and 44, 

 which yielded nearly equal numbers of Calanus and of Centropages; 

 the closing net haul at Station 43, in which there were about as many 

 Euchaeta as Calanus, and Capt. McFarland's haul twelve miles S. E. 

 of Chatham, late in September, in which Pseudocalanus outnumbered 

 Calanus one hundred to one. 



In twelve hauls the copepod constituent of the plankton was ex- 

 clusively Calanus, e. g. in the northeastern part of Massachusetts 

 Bay and off Cape Ann in July; and at the off-shore stations as a whole 

 very few other copepods were found. Thus at Station 7, there were 

 about 1,000 Calanus to one Euchaeta; at Station 23, about 1,000 

 Calanus finmarchicus to six C. hyperboreus to four Euchaeta; at Sta- 

 tion 27, 500 Calanus to two Euchaeta to two Metridia; at Station 28, 

 pure Calanus; and at Station 43, in the open net, 2,000 Calanus to 

 one Euchaeta; cf. table (p. 116). 



Calanus hyperboreus. This Arctic species was taken twice, at Sta- 



