BIGELOW: EXPLORATIONS OV THE COAST WATERS. 307 



Physalia was also seen floating near Stations 10258 and 10202, as 

 well as over the outer part of the shelf south of Marthas \'ineyard in 

 1914; near Brown's Bank (Station 1029()) and in the Eastern Basin 

 of the Gulf (Station 10288) in 1915 (p. 246). 



These siphonophores, and most of the Medusae, are oceanic species 

 which might be expected anywhere in the Gulf Stream or the sub- 

 tropical Atlantic. But two of the medusae, Stomotoca and To.xorchis, 

 are neritic West Indian forms, not previously known north of Florida. 

 Their occurrence at Station 10218 exemplifies the efficacy of the Gulf 

 Stream current as a carrier of tropical organisms. Laodicea is like- 

 wise neritic, but ranges at least as far north and east along the coast as 

 Woods Hole. 



Finally, a single specimen of Diphyes truncata, from Station 10220 

 is worth noting, because this species was not known from American 

 waters, though it is probably cosmopolitan (1913, Moser, 1915). 



Quantitative Distribution of Plankton, 1914, 1915. 



Only on the supposition that the plankton is uniform horizontally, 

 over considerable areas, could a satisfactory quantitati\e survey be 

 expected from vertical hauls as far apart as those of the Grampus; 

 and this is far from true of the plankton of the Gulf, organisms of one 

 sort or another often occurring in streaks, or swarms, for example 

 diatoms in the spring of 1913 (1914b), fish eggs (p. 257), Sagittae 

 (p. 294), and pteropods (p. 298). 



However, this seems to be less often the case with copepods, which 

 are, on the whole, the most important constituent of the Gulf plankton; 

 and since the quantitative hauls show a certain consistenc\- from year 

 to year and from season to season, while nothing whate\er was kno\\'n 

 up to 1912 as to the amount of plankton present in the Gulf, the 

 general results are worth recording. 



The quantitative distribution of plankton may be measured in 

 several ways, the most obvious unit being the total bulk of plankton 

 present from surface to bottom, usually in terras of a column one 

 square meter in cross section. (The area of the mouth of the Hexsen 

 ((uantitative net used in 1914 is .1 square meter: in 1915 we used a 

 Michael Sars net .5 m. in diameter, /. c, with mouth area of approxi- 

 mately .2 square m.). Volume, it is true is a very rough measure 

 (Steuer, 1910), different types of plankton packing down more or less 



