BIGELOW: EXPLORATIONS IN THE GULF OF MAINE. . 127 



was it abundant anywhere. A third genus, Beroe, was Hkewise seen 

 often ; and all the specimens taken belong to the cosmopolitan species 

 B. cucumis, often recorded before from the Gulf. 



Results of the quantitative hauls. 

 (Plate 7). 



In using the Hen sen net for quantitative hauls we were most seri- 

 ously handicapped by working from a sailing vessel, because hauls of 

 this sort are significant only if the vessel is practically motionless when 

 they are taken; and it was impossible to hold the vessel motionless 

 with the auxiliary engine in a breeze. Consequently we could carry 

 on this line of work only at the stations which were occupied in calm 

 weather. Small nets might have been hauled by hand from the dory 

 at anchor; but this was not practicable with the large apparatus with 

 which we were provided. The qualitative composition of the catches 

 made with the Hensen net shows that they did not afford a fair esti- 

 mate of the plankton even under favorable circumstances, because 

 they seldom yielded any Sagittae; organisms which are plentifully 

 represented in the four-foot net hauls. The trouble was, probably, 

 that the nets were hauled too slowly, our hoisting engine reeling in 

 at a rate of only about ten fathoms (about eighteen meters) per 

 minute, which allowed the more active animals to escape. But the 

 copepods, which usually form the bulk of the plankton of the Gulf, are 

 more fairly represented. These shortcomings make it out of the ques- 

 tion to draw any exact conclusion from the hauls. But they serve to 

 show, in a general way, the relative richness of the plankton over dif- 

 ferent parts of the region. The four-foot net hauls, too, help very 

 materially, by supplementing the few quantitative hauls; and although 

 I recognize that the various four-foot net hauls are not directly com- 

 parable with one another, because rate of towing, etc. is never exactly 

 the same at any two stations, and because the level at which the major 

 part of the haul was made, with the open nets, might, or might not 

 coincide with the zone richest in plankton, yet they do show, in a gen- 

 eral way, whether the water was very rich, barren, or intermediate. 

 And the fact that the results agree fairly well with those of the Hensen 

 nets gives them a greater value than they could be credited with if 

 unsupported by this more exact, though less extensive evidence. The 

 four-foot hauls were made as nearly comparable as possible, by being 

 of the same duration (with few exceptions \ hour) ; and by being made 



