726 MINNESOTA BOTANICAL STUDIES. 



region. The measurements given by different authors are as 

 follows : Ruprecht (1. c.), stipe 6-9 inches long, laminae up to 2 

 feet long : Areschoug (1. c.), stipe 30 cm. long, lamina up to 

 one meter in length ; De Toni,* stipe 30 cm. long, lamina up 

 to one meter in length (measurements evidently quoted from 

 Areschoug) ; Hervey (1. c.), stipe 2 or 3 feet long, lamina 2 feet 

 or more long ; Setchell (1. c.), stipe i to 2 feet long, measure- 

 ment of leaves not given; Anderson (1. c.), stipe i to 6 feet 

 long, lamina i to 4 feet long. Of these measurements, Ander- 

 son's is the only one that is approximately correct for the aver- 

 age plant as observed on the Straits of Fuca. 



The first specimen of Pterygophora seen on the Vancouver 

 coast was a battered and eroded stem which had been cast up 

 by the tide. It was between six and seven feet in length and 

 2.5 inches in thickness near the base. Later another specimen, 

 not quite so large, was extracted from a pile of wrack at the head 

 of a little cove and this had a few dilapidated leaves still 

 attached. Examination of the shore yielded several speci- 

 mens, some of which were in an excellent state of preserva- 

 tion, but a few days later some growing beds were discovered 

 and the plant was observed in more detail. Its selection of an 

 habitat is interesting. A favorite place for its development 

 seemed to be on the bottom of deep, narrow chasms in which 

 there was from twelve to fifteen feet of water at low tide. It 

 occurred abundantly on the bottom of a circular hole commu- 

 nicating with the sea by a narrow deep inlet and exposed to 

 heavy surge. It was afterwards found that this was its 

 characteristic position and that it habitually came closer to the 

 rocks than either Nereocystis or Macrocystis. It preferred 

 stations where the water was constantly in motion and did not 

 seem so abundant in quiet coves. As a surge plant it grew 

 lower than Lessonia and it may, perhaps, be described as oc- 

 cupying the lowest position of the surge kelps along this coast. 

 To this precise locality the plant shows certain structural adapta- 

 tions. The holdfast is massive, enabling it to cling firmly to the 

 rocks, notwithstanding the strong movement of the sea. The 

 stem is exceedingly stout being indeed one of the strongest 

 algal structures known and is capable of resisting great 

 tensile strain. While not particularly elastic it is bent from 

 side to side without difficulty or damage to its structure. The 



* De Toni, J. B. Sylloge Algarum, 3 : 352. 1895. 



