272 bulletin: museum of comparative zoology. 



coincided with a decided rise in the saHnity of the surface water 

 (Plate 2). On the other hand Mnemiopsis, together with a few Ae- 

 quorea, Cyanea, and Pleurobrachia, was again numerous at this Sta- 

 tion, and there was a great increase in the number of Salpae (p. 275), 

 which were but sparsely represented at the stations off the mouth of 

 Chesapeake Bay. The hauls at Station 10079 likewise yielded such 

 oceanic genera as Doliolum, Criseis, and Firoloides. Immediately 

 north of Delaware Bay (Station 10080) we once more found swarms 

 of small Salpae (p. 275) and Mnemiopsis, the nets coming in full to 

 the brim. But both of these genera must have been limited to a very 

 shallow surface zone, because a net working about a fathom down 

 caught very few of either. Deeper down, about ten fathoms, the water 

 was occupied by a swarm of Pleurobrachia. Stations 10080 and 10081 

 illustrate how much more varied the plankton was near shore along 

 this part of the coast than in the Gulf of Maine, for no Pleurobrachia, 

 and very few Mnemiopsis were taken at the latter only about forty 

 miles north of the former and about the same distance from land, with 

 about the same temperature and salinity. But the deeper water 

 layers must have swarmed with small Salpae, for the haul at ten fath- 

 oms yielded a perfect Salpa soup; and the surface hauls caught great 

 numbers of Callinectes larvae, which were not represented at all at 

 Station 10080. 



By August 1, Salpae, which were first met in numbers off Barnegat, 

 on the voyage south, had spread northward as far as the Hudson 

 trough (Station 10082) where they formed the bulk of the surface tow. 

 But the haul at twenty fathoms yielded very little except Pleuro- 

 brachia. When the shore of Long Island (Station 10083) was ap- 

 proached, the Salpae, and the Pleurobrachia swarm, were replaced 

 by a rather scanty copepod plankton. 



The remainder of the work was carried on in the Gulf of Maine. 

 And no sooner had the Grampus rounded the southern angle of Cape 

 Cod (Station 10085) than the boreal plankton, with which we are 

 familiar from previous work in the Gulf, was encountered. Stations 

 10057 and 10086 were located at the same geographic position off 

 Highland light, and the only apparent change which had taken place 

 during the interval of four weeks which separated them was that the 

 Staurophora, Stephanomia, and Beroe, which had been prominent in 

 the tow early in July were no longer found. Off Massachusetts Bay 

 we found a typical Calanus plankton, with Euchaeta norvegica, north- 

 ern schizopods, Sagitta elegans, Euthemisto, Limacina halea, Pleuro- 

 brachia, Melicertum, Tomopteris helgolandica, Euchaeta, and hosts of 



