vol.i] Setchell— Gardner. — Alga of Northwestern America. 263 



young plants have a short stipe, while the older plant becomes 

 eucullate at the base of the blade, which sends out hapteres. 

 This continues as the plant grows older, the blade continuing 

 to expand at the base, to form new rows of hapteres, thus 

 becoming more sessile and prostrate in this region, wider 

 and more split above, until it forms dumps of sessile fronds 

 sitting upon masses of clustered hapteres. The plants of 

 the lower parts of its habitat have smooth blades, but those of 

 the upper parts often have the blades bullate and irregularly 

 rugose. The sori form indefinite patches over the base of the 

 entire frond. 



Hedophyllum subsessile (Areschong) Setchell. Plate 20. 



On rocks, usually forming a zone in the middle literal zone. 

 Kyska Island. Alaska, Townsend, No. 5770!; west shore of 

 Amaknak Island. Bay of Unalaska, Alaska, TP.A.iS'. and A.A.L., 

 No. 3286!, L. E. Hunt, No. 3250!, in Collins, Holden and 

 Setchell, P. B.-A., Xo. xxyh! ; Uyak Bay, Kadiak Island, Alaska, 

 W.A.S. and A.A.L., No. 5078! ; Kukak Bay, Alaska, Saunders 

 (1901, p. 430); Prince William Sound, Alaska, Saunders, No. 

 259!; Yakutat Bay. Alaska, Saunders, No. 218!; Puget Sound, 

 Saunders (1901. p. 430). 



The present species is widely diverse from any form which can 

 be legitimately reckoned under L. Bongardiana, to which Ares- 

 choug referred it as a form. It comes near to Hedophyllum sessile 

 in its earlier stages of growth, but soon departs from that species 

 in that the central portion of the blade wears away, leaving the 

 bases of the blade on each side of the original short stipe as 

 thickened, rhizome-like, creeping structures bearing the blades, or 

 half blades, at their tips (cf. pi. 20). The peculiar dying 

 away of the center of the blade to the very base and the con- 

 sequent thickening of the basal margins, is known in Eisenia 

 (cf. Setchell, 1896) and in Thalassiophyllum as described below. 

 The present species lacks the scrolls or auricles at the base of the 

 blade characteristic of Arthrothamnus. The development of the 

 members of the last genus is not known as yet, and may be quite 

 different from that of Hedophyllum, if one may judge from 

 specimens of the adult plants. While we have noted localities 



