L925] Setchell-Gardner : Melanophyceae (ill 



9. Fucus furcatus f. nigricans Gardner 



Fronds comparatively fragile, thin membranaceous, 35-45 cm. 

 high, regularly dichotomous, dark olive green, black on drying, angles 

 broad and slightly rounded ; segments cuneate below, linear above, 

 reduced to a midrib 4-5 segments back of the apices, widest 3-4 back 

 of the apices, reduced in width at each forking, widest 18-24 mm., 

 midrib narrow but distinct, percurrent, alae thin, caecostomata 70-80 

 per sq. em., small, obscure; receptacles 2.5-3.5 cm. long, complanate or 

 inflated, single or bifid, definitely delimited, apices mostly acute and 

 mostly reflexed. 



Growing on boulders and rock ledges in the middle of the littoral 

 belt. Cattle Point, south end of San Juan Island, Washington. 



Gardner, Genus Fucus, 1922, p. 21, pi. 8. 



In the cornute habit, forma nigricans is closely akin to forma 

 cornutus, but differs from it in the following characters; thinner 

 fronds which are more cartilaginous, darker color, black on drying, in 

 having widely divergent segments and in having an abundance of 

 caecostomata. 



10. Fucus furcatus f. cornutus Gardner 



Fronds subcoriaceous, 20-30 em. high, regularly dichotomous, dark 

 olive green to dark olive brown, black on drying ; segments divergent, 

 linear, or very slightly cuneate in the narrower specimens, varying to 

 decidedly cuneate in the wider specimens, 5-8 mm. wide, apices acu- 

 minate, truncate, midrib well developed, prominent, very slightly 

 evanescent above, alae narrow, caecostomata very sparse, 10-20 per 

 sq. cm., small ; receptacles distinctly delimited, very variable, com- 

 planate or inflated, usually much wider than the segments, simple or 

 bifurcate, 2-4 cm. long, blunt to acuminate, apices mostly laterally 

 reflexed ; conceptacles not numerous, inconspicuous. 



Growing on rocks in the middle and lower littoral belts. From 

 Yakutat Bay, Alaska, to Victoria, British Columbia. 



Gardner, Genus Fucus, 1922, p. 20, pi. 7. Fucus evanescens f. 

 cornutus Saunders, Alg. Harriman Exp., 1901, p. 432, pi. 62, fig. 2; 

 Collins, Mar. Alg. Vancouver Isl., 1913, p. Ill ; Collins, Ilolden and 

 Setchell, Phyc. Bor.-Amer. (Exsicc), no. 927. 



The narrow fronds with prominent midribs and the very dark color 

 make this form close to certain narrow forms of edcntatus, but the 



