380 
BULLETIN OF THE BUREAU OF FISHERIES 
our surface net took great numbers of them over the northwest part of the bank 
(station 10059). These were submitted to Dr. C. McLean Fraser for study, and 
the reader is referred to his report (in Bigelow, 1915, pp. 268 and 306) for details. 
It will suffice to say here that the catch of hydroids was not only considerable in 
amount but included no less than 13 species, belonging to 4 families. Most of these 
were represented by broken fragments only, or by colonies attached to bits of eel- 
grass (Zostera) ; but the hundreds of colonies of Clytia cylindrica (the predominant 
species) were floating free of any support, and not only in a perfectly healthy state 
as far as appearances go, but so completely regenerated that there were few or no 
broken ends visible. 
As it can hardly be supposed that these colonies had passed through their 
whole development, from the planula stage onward, at the surface of the sea, the most 
reasonable explanation for their presence afloat is that they had been torn from 
their attachments on the bottom by the strong tidal currents and kept suspended 
in the water by this agency. Finding a rich food supply in their pelagic surround- 
ings, with nothing fatal in such an environment, they regenerate, grow, and even 
propagate their kind, as appears from their development of gonophores. After all, 
there is nothing surprising in such a phenomenon, for it is "not unusual to find 
fragments of hydroid colonies torn from their support or from the rest of the colonies, 
living for a considerable time as they float on the surface” (Fraser, 1915, p. 307). 
Similar congregations of floating hydroids have been encountered thrice since 1913, 
always on Georges Bank — viz., July 23, 1914 (station 10224), July 23, 1916 (stations 
10347 and 10348), and February 23, 1920 (station 20047). Judging from the geo- 
graphical grouping of these stations (fig. 98) their place of origin is probably on the 
shallows known as "Georges” and the " Cultivator” Shoals. 
