BIGELOW: OCEANOGRAPHY OF MASSACHUSETTS BAY. 415 
in all directions. No doubt the strong tides and currents which flow 
over the Bank keep them afloat. ‘They were submitted to Prof. S. F. 
Clarke for identification, and will be described more fully elsewhere. 
Large numbers of haddock eggs, nearly ready to hatch, were like- 
wise found in the haul. The microplankton was decidely more 
abundant than the larger organisms, so much so, that, according to 
Mr. Douthart’s accounts, the nets were soon clogged, although of 
large mesh. And he further noted that it was in streaks, not uni- 
formly distributed. On microscopic examination, the mass proved 
to consist of diatoms; but qualitatively it was far more complex than 
the diatom swarm near shore, while the chief role was played by 
various species of Chaetoceras, especially C. densum, C. atlanticum, 
and C. decimens, instead of by Thalassiosira, although 7. norden- 
skioldi and T. gravida were both abundant. Other conspicuous 
species are Datylum brightwellu, Rhizosolenia obtusa, R. styliformis, 
R. semispina, Thalassvothrix nitzschioides, Coscinodiscus, Coscinosira 
Asterionella japonica, with large numbers of Pleurosigma. 
A little more than a week later, Mr. Douthart made a second series 
of tows on the western side of the Bank (p. 419), which showed that 
the macroplankton was apparently less abundant; and though it was 
of the same general type as before, Temora was about as abundant as 
Calanus. But the fact that the hauls were restricted to the surface 
makes it doubtful whether apparent variations in the relative numbers 
of different organisms have any real meaning. Other characteristic 
members of the plankton were Sagitta elegans, Oikopleura, the cam- 
panularian hydroids noted above, Actinian larvae, Hybocodon, 
Pleurobrachia pileus, and many haddock eggs. The microplankton 
was quantitatively as rich as on the last visit; but it had undergone a 
decided change qualitatively, its most important component, numeri- 
cally, now being Rhizosolenia styliformis. In the last haul, this form 
was represented by occasional examples only; now it formed the 
greater part of the mass; and many of the specimens were so large 
(1.1 mm.) as to be easily visible with the naked eye. 
