474 



BULLETIN OF THE BUREAU OF FISHERIES. 



out the sublittoral, the flora of the bottom of the Bay and Sound must be very different 

 indeed from that of the summer. Especially interesting are the series of studies of 

 the flora of Spindle Rocks, Woods Hole, which were made at intervals throughout a 12- 

 month cycle in 1904 and 1905. These are described in the next section of this paper. 

 Such intensive studies over long periods of time are very much to be desired to determine 

 the seasonal changes in algal floras. 



We give below a list of the algae so far known to be present in the cold-water 

 sublittoral formation of the winter and spring: 



P. leucosticta. 

 Chantransia secundata. 

 C. virgatula. 



Antithamnion americanum. 

 Callithamnion Baileyi. 

 Ceramium rubrum. 

 Polysiphonia fastigiata. 

 P. nigrescens. 

 P. urceolata. 

 Rhodomela Rochei. 

 R. subfusca. 

 Ahnfeldtia plicata. 

 Chondrus crispus. 

 Sterrocolax decipiens. 

 Rhodymenia palmata. 

 Gloiosiphonia capillaris. 

 Rhododermis Georgii. 



The cold-water sublittoral formation accepts a winter temperature, which for at 

 least two and a half months probably averages under 35° F. , as indicated by the records for 

 Great Harbor, Woods Hole (the average temperature between December 25 and March 

 15 for the years 1 902-1 906 was below 35°). Many of the species of this formation reach 

 their best vegetative condition and fruit during the spring, and then pass out of season. 

 During this period the temperature of the water rises steadily, passing 60° about June i . 



THE LITTOE^AL FORMATIONS. 



As has been stated before, the algal growths in the littoral region are not very 

 striking in the immediate vicinity of Woods Hole, chiefly for these reasons, (i) that the 

 tides are small, (2) that the shore line is very broken, (3) a marked boreal flora is 

 absent, and (4) the scraping of floating ice in the winter prevents the development of 

 an extensive littoral flora at this season. Neighboring coasts exposed sufficiently as to 

 be free from floating ice, as at Cuttyhunk, have heavy growths of algae in the winter, but 

 there have been no opportunities for thorough studies at this season. These growths 

 are, however, undoubtedly composed largely of rockweeds (Fuciis and AscophyUum). 



The littoral formations of the different seasons at Woods Hole are of a very spotted 

 character, rarely being so extensive as to attract attention and generally breaking up at 

 once into small associations. Of these the following are at times very evident: The 

 Calothrix associations (3), the RivuLaria associations (4), the Pleurocapsa association 



