BIGELOW: EXPLORATIONS IN THE GULF OF MAINE. 131 



Station 44 and off Marshfield consisting of a few Ceratium tripos, 

 with no diatoms at all, but a large amount of dirt and debris, and 

 copepod eggs. It appears, then, that the water of the northern half 

 of Massachusetts Bay, throughout July and August, was occupied by 

 a very scanty Ceratium plankton, with very few diatoms. 



North of Cape Ann the same scanty Ceratium plankton was found 

 occupying a belt some fifteen miles broad, as far north as Cape Por- 

 poise, both in July (Stations 9, 11, 12b, 13) and on the return, late in 

 August (Station 41). But in Ipswich Bay, just north of Cape Ann, 

 close to land (Station 8), the plankton, though equally scanty, was 

 mixed, containing a considerable number of diatoms, especially vari- 

 ous species of Chaetoceras, and Asterionella japonica, which gives it a 

 character quite distinct from that of Massachusetts Bay, or from the 

 neighboring stations further off shore. 



No station was occupied immediately abreast of Cape Ann on the 

 voyage north; but on the return, August 24, we made a haul some 

 four miles off the Cape (Station 42), finding an almost pure Ceratium 

 plankton, with very few diatoms. But though qualitatively this 

 agreed with Massachusetts Bay, it was considerably richer quantita- 

 tively, than at any of the stations immediately north or south of 

 the Cape. This was likewise true of our hauls over the western arm 

 of the deep basin in early July (Station 7), and off Cape Cod at the 

 end of August (Station 43). At both of these, Ceratium tripos was 

 the prevailing organism; and with it were large numbers of Peri- 

 dinium, but no Chaetoceras or Asterionella. Inasmuch as the 

 samples taken at the two stations are hardly distinguishable from 

 each other, either qualitatively or quantitatively, it is fair to assume 

 that they represent the characteristic facies of the summer micro- 

 plankton for the general region which they cover; one distinctly 

 richer in mass, as well as in species, than that found in Massachusetts 

 Bay; but with the same organism, Ceratium tripos, occupying the 

 leading position, and with equally few diatoms. 



The Ceratium plankton reached its maximum density over a roughly 

 oval area southwest of Cape Elizabeth (Plate 8), which we traversed 

 twice, (Stations 19, 22, 23, 26b) with an interval of seven days be- 

 tween our two visits. On our second visit, when running our line 

 to Nova Scotia we were struck by the "slick" oily appearance of the 

 water, some thirty-five miles off Cape Elizabeth; and consequently 

 stopped the vessel for a surface tow (Station 26b). The net, when 

 brought aboard, was distinctly reddish, and its meshes clogged with 

 what proved to be a mass of Ceratium, with a very few Peridinium, 



