BIGELOW: COAST WATER EXPLORATION OF 1913. 277 



may note that great numbers of this species were taken by fishermen 

 in Massachusetts Bay in the ensuing November and December. The 

 commonest species was S. democratica. It was not taken over the 

 edge of the shelf south of Nantucket and Long Island. But it swarmed 

 on the surface off Barnegat (Station 10069) ; and was taken at all the 

 stations further south, though it was far less abundant in the Gulf 

 Stream than at certain localities near land, e. g., Stations 10069, 

 10075, 10079, 10080, 10081, and 10082. But it was not universally 

 common over this part of the shelf, there being regions of scarcity 

 off Delaware Bay and off Chesapeake Bay (Stations 10070, 10072, 

 10074, 10078). All the captures were from temperatures higher than 

 65°. Salinity was about the same (32.1%o-32.4%o) at several of the 

 poor Stations (10070, 10072) as at several rich ones (10069, 10079, 

 10080, 10081) ; and the total range of salinity occupied by the species 

 was very great (32.27%o to 35.25%o). The unequal quantitative dis- 

 tribution of Salpo democratica is, I believe, an index of the abundance 

 of the food supply, not of the amount of Gulf Stream water. Dur- 

 ing the early summer the surface temperature rises sufficiently to make 

 the coast water a favorable habitat for the Salpae which are dispersed 

 over this part of the continental shelf by the constant mixture between 

 land and Gulf Stream water, and wherever they find a plentiful food 

 supply, they reproduce with marvelous rapidity. Examination of the 

 intestinal contents of S. democratica supports this view, for the speci- 

 mens taken at Stations 10069, 10077, 10081 contain large amounts 

 of diatom and peridinian debris. Salpa democratica occasionally 

 swarms in the Gulf of IMaine, for example, off Chatham in September, 

 1912 (1914a), though not encountered there in 1913. 



The five other species of Salpa do not agree in distribution with S. 

 democratica, for they were all absent in the coastal belt south of New 

 York, (Stations 10069, 10075, 10078 off Hog Island, 10079, 10080, 

 10081 and 10082), i. e., just where democratica was most abundant (p. 

 275) . Salpa zonaria was second to democratica in the number of sta- 

 tions at which it was observed, but unlike the latter, it was most 

 abundant at the edge of the Gulf Stream and over the outer part of 

 the shelf (Stations 10064, 10071, 10072, 10074); absent close to land. 



Salpa fusiformis was even more restricted to the edge of the Gulf 

 Stream, being most abundant in the deep hauls at the Stations where 

 Gulf Stream water was purest (10064, 10071), much less *so off Chesa- 

 peake Bay Station (10076). It was not found anywhere over the 

 continental shelf, except a few specimens at Station 10070. 



Our only capture of S. cylindrica was at the most typical Gulf 

 Stream Station (10071), where it was numerous, far outnumbering 



