478 BULLETIN OF THE BLIREAU OF FISHERIES. 



when exposed to similar ice scraping and shows clearly why the littoral flora in mid- 

 winter is so little developed in this region. Returning to chart 267, it will be seen that 

 the algae were all below low-water mark, the most conspicuous forms being Cerammm 

 riibrum (43) and Chondrus crispus (49), forming a zone around the rocks. 



The group of rocks a month later presented a very different aspect, as shown in 

 chart 268, recorded on April 22. Cladophora lanosa var. uncialis (11) had appeared in 

 considerable quantity near low-water mark, and somewhat lower down was an imperfect 

 zone consisting of young growth of PhyUitis fascia (24) and Scylosiphon lomcntarius (26). 

 Polysiphonia urceolata (47) had appeared well below low-water mark and was the most 

 conspicuous member of a zone of red alga, including Ccramium rubrum (43) and Chondrus 

 crispus (49). There were present Sorocarpus uvoeformis, four species of Ectocarpus, and 

 the two species of Desmotrichum, all new to the rocks, showing how quickly such algae, 

 reproducing by zoospores, may establish themselves. A notably new form was Chorda 

 iomcntosa (32), which had begun to appear. 



Chart 269, recorded May 22, shows the conditions after another month, and when the 

 spring flora was at its full development. Cladophora lanosa var. uncialis (11) was still 

 the dominant green alga, but Entcromorpha intestinalis (7) had begun to appear, and these 

 two algae had extended the green zone much higher on the rocks than at the previous 

 date, April 22 (chart 268). The brown zone at low-water mark, composed chiefly of 

 Ectocarpus penicillatus (iS), PhyUitis fascia (24), Scyiosiphon lomcntarius (26), and 

 Chordaria flagelliformis (28), was much more evident. Polysiphonia urceolata (47) was 

 very conspicuous in the zone of red algae below the brown. Chorda tomcntosa (32) was 

 abundant. 



Conditions were very greatly changed after another month, as shown in chart 270, 

 recorded June 29, the spring flora having given place to the beginning of the summer 

 flora. Cladophora lanosa var. utKialis had entirely disappeared, and the prominent 

 green zone above low- water mark was composed of Ulothrix implexa (3) and Enteromorpha 

 intestinalis (7), with young growths of Ulva Lactuca var. rigida (5). The brown zone 

 near low-water mark was now chiefly Scytosiphon lomcntarius (26) and Chordaria flagel- 

 liformis (28); PhyUitis fascia was represented by only a few old plants and Ectocarpus 

 penicillatus had disappeared. The other species of Ectocarpus, Desmotrichum, and 

 Sorocarpus uvceformis, as well as Chorda tomcntosa, were also no longer present. Polysi- 

 phonia urceolata had disappeared, its place being taken by Polysiphonia violacea (48), 

 which with Ceramium rubrum (43) and Chondrus crispus (49) chiefly composed the zone 

 of red alg£e below the brown zone. Nemolion multifidum (40), a characteristic summer 

 species, had begun to appear at and above low-water mark. 



The typical summer flora is shown on chart 271 , recorded July 22. The conspicuous 

 green alga was Ulva Lactuca var. rigida (5), growing in large patches with other green 

 algae in small quantities. There was a well-defined brown zone just above low water 

 composed chiefly of Chordaria flagelliformis (28) and Scytosiphon lomcntarius (26), both 

 bearing Ectocarpus confcrvoidcs (14) as a conspicuous epiphyte; PhyUitis fascia had dis- 

 appeared. Nemalion multifidum (40) was now plentiful, fringing the rocks at low-water 

 mark. Below the brown zone and mixed with it were abundant growths of Ceramium 

 rubrum (43), Polysiphonia violacea (48), and Chondrus crispus (49). Chart 272, recorded 

 September 2 , is similar to chart 271, but with certain features more pronounced. The most 



