726 MINNESOTA BOTANICAL STUDIES. 
region. The measurements given by different authors are as 
follows: Ruprecht (I. c.), stipe 6-9 inches long, laminz up to 2 
feet long; Areschoug (I. 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 (I. c.), stipe 2 or 3 feet long, lamina 2 feet 
or more long; Setchell (1. c.), stipe 1 to 2 feet long, measure- 
ment of leaves not given; Anderson (lI. c.), stipe 1 to 6 feet 
long, lamina 1 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 Vereocystis 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 Lessonza 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. 
