BIOLOGICAL SURVEY OF WOODS HOLE AND VICINITY. 



473 



*Cladophora gracilis and occa- 

 sionally other species. 



Ascocyclus orbicularis (o). 

 *Ectocarpus confervoides. 



E. penicillatus. 

 *E. siliculosus. 



Sphacelaria cirrhosa (o). 

 *Desmotrichum balticum (in the 



spring). 

 *D. undulatum (in the spring), 



Pogotrichum filiforme (o). 

 *Punctaria latifolia. 



Rhadinocladia Farlowii (o). 



Giraudia sphacelarioides (o). 



Castagnea virescens (o). 

 *C. ZostersE. 



Hccatonema maculans (o). 



Myrionema vulgare. 



vStilophora rhiz )des (o). 



Erythrotrichia ccramicola. 

 *Porphyra Ic.icosticta (in the 

 spring). 



Chantransia secundata. 

 *C. virgatula. 



Antithamnion cruciatum (in 

 deep water). 



Callithamnion Baileyl. 



C. Bailcyi var. laxum. 

 *C. byssoidcum. 

 *C. corymbosum. 

 *C. roseum. 

 *Ceramium fastigiatum. 



C. rubrum. 

 *C. strictum. 

 *C. tenuissimum. 

 *Seirospora Griffithsiana. 

 *Sp)Tidia' filamentosa (o). 



Chondria dasyphylla (o). 



Chondria sedifolia (o). 

 *Dasya elegans. 

 *Polysiphonia Harveyi. 

 *P. Olneyi. 



P. variegata (o). 



Rhododcrmis Georgii (o). 



Mclobesia farinosa. 

 *M. Lejolisii. 



The Zostera formation endures temperatures considerably higher than those given 

 for the range of the warm-water sublittoral, especially where the eel grass grows in. 

 coves or other sheltered stations. Such waters may remain above 70° F. for many 

 days, probably at times reaching as high as 75° to 78°. These conditions as to heat 

 are the most extreme of any in this region, except of course the small brackish pools 

 and ditches of the salt marshes. 



A WINTER SUBLITTORAL FORMATION. 



It is clear that, as the temperature of the Bay and Sound falls during the autumn, 

 the conditions become less favorable for the warm-water sublittoral flora. Many species 

 characteristic of waters south of Cape Cod pass out of season, although certain species 

 which may be said to endure the summer's heat are at their best in the winter season. 

 A cold-water winter sublittoral formation is thus developed, which extends throughout 

 the Bay and Sound, reaching its best development probably in the late winter and early 

 spring. 



We know nothing of this winter and spring flora in the deeper waters of the Bay 

 and Sound, for there have been no dredgings for algae at these seasons. The cool-water sub- 

 littoral formation of the lower portion of the Bay and westerly portion of the Sound would 

 be expected to enter the more sheltered regions occupied by the warm-water sublittoral 

 during the summer, but how far it may extend is a matter of conjecture. Undoubtedly 

 species appear which are not present in either Bay or Sound during the summer, some 

 probably developing from resting spores that carry the forms through the summer, and 

 others coming in by means of spores brought from a distance. 



It is probable that numbers of northern species, the spores of which might be brought 

 from a distance, would be able to estabUsh themselves, develop to maturity, and perhaps 

 pass through several generations before the temperature rises sufficiently in the spring 

 to put an end to their growth. Species of Cladophora, Ectocarpus , and other rapidly 

 growing green and brown algae, reproducing by zoospores, are admirably fitted for a 

 periodical winter invasion, and some of the smaller red algse which mature quickly 

 would also be expected to take part in such a migration. 



Some observ^ations on the algal vegetation along shore in shallow water have been 

 made during the winter and spring, and if these are indices of the general change through- 



