132 bulletin: museum of comparative zoology. 



and an occasional diatom; and this phenomenon continued for several 

 miles. 



x\t Stations 19, 22, 23, Ceratium was not so phenomenally plentiful; 

 but still far more abundant than at any station further to the south; 

 and the microplankton was almost pure Ceratium tripos, with an oc- 

 casional Peridinium, but few, if any, diatoms; though it contained a 

 considerable amount of copepod eggs, fish eggs, nauplii, etc., cor- 

 responding to the rich macroplankton encountered there (p. 101). 

 Further east, on Jeffrey's Bank, the microplankton was much less 

 abundant, but still mostly Ceratium tripos, with a very few diatoms, 

 among which I noted the genus Chaetoceras, and the characteristic 

 needle-like chains of Nitzschia seriata. 



Along the coast from Casco Bay to the mouth of Penobscot Bay 

 (Stations 16, 21) there were, on the other hand, very few Ceratium, 

 but the microplankton, which was fairly rich, in contrast with a very 

 scanty macroplankton, consisted almost wholly of diatoms, the princi- 

 pal forms being various species of Chaetoceras, Thalassiosira gravida, 

 Nitzschia seriata, and Asterionella japonica. Over the eastern arm of 

 the deep basin (Stations 27, 28), the pure Ceratium plankton character- 

 istic of the waters further west gave way to a mixed plankton, rather 

 poor quantitatively, in which Ceratium was associated with a few 

 Peridinium and various diatoms, among them several species of Chaeto- 

 ceras, and Thalassiosira gravida. And a similar type, but quantita- 

 tively richer, was revealed by our hauls on German Bank (Stations 

 29, 30), where several species of Chaetoceras, Rhizosolenia setigera 

 and other species of the genus, and Thalassiothrix were especially 

 prominent in the hauls. These two stations were within a few miles 

 of each other, and it is therefore interesting to note that at Station 29 

 the plankton was far richer, both quantitatively and in species, than at 

 Station 30; and that Ceratium played, proportionately, a greater 

 role. However, the microplankton at both these stations, and over the 

 eastern basin (Stations 27, 28) can be classed as Ceratium with a 

 large admixture of diatoms, the latter probably of neritic origin for 

 the most part. 



At Station 31, off Lurcher Shoal, the microplankton was very 

 scanty, consisting chiefly of minute copepods and their eggs, apd 

 nauplii; but there were a few Ceratium and diatoms, especially 

 Chaetoceras and Asterionella, i. e., it was of the mixed type. And much 

 the same thing was encountered off Mt. Desert Rock (Station 32), but 

 quantitatively rather richer, the two most prominent organisms being 

 Ceratium tripos, and the diatom Asterionella, with a few Chaetoceras 



