BIGELOW: COAST WATER EXPLORATION OF 1913. 269 



yielded many Euthemisto, the rest of the catch consisted of such 

 typical Gulf Stream species as small "black fishes" (Myctophidae), 

 swarms of Salpae of several species (p. 275), Doliolum, Phronima, 

 Vibilia, Saphirrina and other species of copepods not taken in the 

 cold waters nearer shore (p. 296) ; and such typical warm water coelen- 

 terates as Rhopalonema velatum, Physophora hydrostatica, and Agalma 

 elegans (p. 316). But the haul from twenty-five fathoms yielded 

 little except hundreds of colonies of Agalma elegans, with only a few 

 Salpae; and the surface water was practically barren. Along this 

 part of the coast Gulf Stream fauna was confined to the waters outside 

 the continental shelf, for as we ran shoreward once more a typical 

 Calanus plankton in great abundance was encountered, together with 

 other boreal organisms, over the forty fathom curve (Station 10065). 

 Cape Cod is often spoken of as the dividing line between warm 

 and cold water faunae on our coast; but at the time of the cruise it 

 was not until we neared New York that any decided change in the 

 character of the plankton of the coast water was noted. East of this, 

 and in the Gulf of Maine (p. 285), copepods, chiefly Calanus, every- 

 where played an important role, though occasionally overshadowed 

 by the extraordinary abundance of some other organism, for example, 

 the hydroids on George's Bank, and the swarms of Euthemisto south 

 of Block Island. But they were a very insignificant part of the 

 plankton south of New York and were occasionally entirely lacking 

 in the hauls. Near New York (Stations 10067 and 10068) the water 

 was filled with swarms of Plcurobrachia pileus to the exclusion of 

 almost everything else, except on the immediate surface, where the 

 no. 20 net brought back a considerable number of small copepods 

 (Centropages typicus). A few miles further south (Station 10069) 

 large numbers of Salpae (p. 277) were seen on the surface close to land. 

 At this Station, too, swarms of the large warm water ctenophore, 

 Mnemiopsis leidyi, which has never been known to enter the Gulf of 

 Maine, but which is common along shore as far as Cape Cod later 

 in the summer, were noted for the first time. Other interesting 

 coelenterates, common near the surface at this Station and further 

 south, are the well-marked southern variety of the large hydromedusa, 

 Aequorea groenlayuUca, and the pale southern Cyanea (p. 315). But 

 all these warm water forms seem to have been limited to a shallow 

 surface zone, because the haul from fifteen fathoms yielded great 

 numbers of Pleurobrachia pileus, but no Salpae or Mnemiopsis, and 

 only a few Aequorea which were probably caught near the surface. 

 Besides the Pleurobrachia there were about twenty Aglantha digitale 



