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BIOLOGICAL SURVEY OF WOODS HOLE AND VICINITY. 539 
Pyramid Rock 
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CHART 269.—Distribution of alge 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 
intestinalis (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 
lomentarius (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, 11, 
abundant; Ectocarpus fasciculatus, 15, abundant on larger alge; Ectocarpus penicillatus, 18, abundant on 
larger algee; Sorocarpus uveformis, 21, few on mussel shells; Desmotrichum balticum, 22, few mixed with 
Scytosiphon; Desmotrichum undulatum, 23, few mixed with Scytosiphon; Phyllitis fascia, 24, very abun- 
dant; Punctaria plantaginea, 25, few; Scytosiphon lomentarius, 26, abundant; Desmarestia viridis, 27, 
very abundant; Chordaria flagelliformis, 28, much; Chorda tomentosa, 32, abundant; Laminaria A gardhii, 
33; Ceramium rubrum, 43, abundant; Polysiphonia urceolata, 47, abundant; Polysiphonia violacea, 48, 
few; Chondrus crispus, 49, abundant. 
