BIOLOGICAL SURVEY OF WOODS HOLE AND VICINITY. 



539 



Chart 269. — Distribution of algse on Spindle Rocks, May 22, 1905. 



The rocks at this date presented a characteristic algal flora of the spring at its full development. 

 There was not much change in the species since April 22 (chart 268), but a large increase in the quantity 

 of vegetation. Cladophora lanosa var. uncialis (11) was still the dominant green alga, but Enteromorpha 

 iniestinalis (7) had begun to appear; these two species extended the green zone much higher up on the 

 rocks than where it was a month previous (chart 268). The brown zone at low-water mark (the dotted 

 line) and just below, composed chiefly of Ectocarpus penicillatus (18), Phyllitis fascia (24), Scytosiphon 

 lomenlarius (26), and Chordaria flagelliformis (28), was also broader and more evident. Polysiphonia 

 urceolata (47) formed a conspicuous red zone below the brown, with extensive growths of Chondrus 

 crispus (49) extending into deeper water. 



List of species: Enteromorpha intestinalis, 7, young plants; Cladophora lanosa var. uncialis, n, 

 abundant; Ectocarpus fasciculatus, 15, abundant on larger algae; Ectocarpus penicillatus, 18, abundanton 

 larger alga; Sorocarpus uvceformis, 21, few on mussel shells; Desmotrichum balticum, 22, few mixed with 

 Scytosiphon; Desmotrichum undulalum, 23, few mixed with Scytosiphon; Phyllitis fascia, 24, very abun- 

 dant; Punctaria planiaginea, 25, few; Scytosiphon lomentarius, 26, abundant; Desmarestia viridis, 27, 

 very abundant; Chordaria flagelliformis , 28, much; Chorda lomeniosa, 32, abundant; Laminaria Agardhii, 

 33; Ceramium rubrum, 43, abundant; Polysiphonia urceolata, 47, abundant; Polysiphonia violacea, 48, 

 few; Chondrus crispus, 49, abundant. 



