BIOLOGICAL SURVEY OF WOODS HOLE AND VICINITY. 479 



prominent zone (much more conspicuous than in chart 271) was just below low water and 

 composed of Ceramium rubrum (43) and Polysiphonia violacea (48), these two forms 

 having taken the region formerly occupied by the brown zone. Chart 273, recorded Sep- 

 tember 19, 1904, a year previous to the last, is interesting because there was no Chordaria 

 ftagelliformis that season and very little Polysiphonia violacea, but an abundance of 

 Polysiphonia fibrillosa (46), which took the place of the first two species, forming with 

 Ceramium rubrum (43) a dense zone below low-water mark. 



The conditions at the beginning of the winter and before the rocks were scraped 

 by floating ice are shown in chart 274, recorded December 30, 1904. This chart in the 

 sequence follows chart 273, of September 19, 1904, and precedes chart 267, of March 17, 

 1905, by two and one-half months. The prevailing green alga was Cladophora lanosa 

 var. uncialis (1 1), which had taken the place of Ulva Lactuca var. rigida (5), so abundant 

 in the summer, but now only represented by the bases of old plants. The brown zone 

 was composed of Phyllitis fascia (24) and Scytosiphon lomentarius (26) ; there was no 

 Chordaria flagclliformis. Ceramium rubrum (43) was abundant below the brown zone 

 but Polysiphonia fibrillosa (46) had almost disappeared. Two species of Ectocarpus were 

 present, together with several other epiphytic brown and red algae. 



A close study of this series of charts will show very graphically the general nature 

 and extent of the seasonal changes that must take place on very many ledges and groups 

 of rocks along the coast, and similar seasonal changes would be expected wherever there 

 is a well-developed littoral and sublittoral flora near low-water mark. Intensive studies 

 of this character of well-chosen situations are far more important for our knowledge of 

 seasonal habits and algal successions than random collecting undertaken along the shore. 

 It is much to be desired that such work be systematically undertaken by those in a 

 position to make detailed records over extended periods. Perhaps this brief record of a 

 study (abruptly terminated by the destruction of the selected station), which shows 

 such interesting results, will lead others to make similar investigations. 



In conclusion we wish to acknowledge our indebtedness to Miss Lillian J. MacRae, 

 who, with the assistance of Mr. Collins, made the records of several charts at seasons 

 when it was impossible for us to be at Woods Hole. 



