BIGELOW: EXPLORATIONS IN THE GULF OF MAINE. 131 
Station 44 and off Marshfield consisting of a few Ceratiwm tripos, 
with no diatoms at all, but a large amount of dirt and débris, 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, 
