vol. ] Setchell— Gardner . — Alga' of Northwestern America. 363 



B. C, Yendo (1902, pp. 715, 716, under Cheilosporum fron- 

 descens ff.) ; East Sound. Oreas Island, Wash., X.Z.G., No. 916! ; 

 west coast of Whidbey Island, Wash., X.L.G., Nos. 80!, 82! 



While in some cases, the present form is fairly distinct from 

 the nest, in many cases, it is difficult to decide to which form to 

 refer a given specimen. Yendo has recognized this when he says 

 (1902. p. 717) : — ''Nevertheless, it would not be an unreasonable 

 supposition that the hybrid between Gheil . frondescens and Gheil. 

 planiusculum may occur in nature." He also recognizes the. 

 variability of the plants placed under each by the number of 

 forms which he describes or refers to. The stipe, upon whose 

 length and thickness he depends for one essential difference 

 between the two, varies much and at times seems interchanged. 

 We regard this as a very unreliable character. The apical joints 

 and the thickness or thinness of their external margins do not 

 always lead us safely, and the approximation or non-approxi- 

 mation of the joints seems as little satisfactory. We have 

 retained the two forms and are able to separate them to a certain 

 degree, but not satisfactorily. 



Amphiroa tuberculosa f. planiuscula (Kuetzing) Setchell 

 and Gardner comb, no v. 



On rocks in the lower literal zone, also in shallow pools in the 

 upper literal zone. Near Iliuliuk, Unalaska, Alaska, W.A.S. and 

 A.A.L.. No. 4057 ! ; Uyak Bay, Kadiak Island, Alaska, W.A . S. and 

 A.A.L.. No. 5096! ; Harvester Island, Uyak Bay, Kadiak Island, 

 Alaska. W.A.S. and A.A.L., No. 5128! ; Prince William Sound 

 and Sitka, Alaska, Saunders (1901, p. 442, under Amphiroa 

 planiuscula); Port Renfrew, B. C, Yendo (1902, p. 717, under 

 Cheilosporum planiusculum), Tilden, No. 503!, under Cheilo- 

 spomm planiusculum; west coast of Whidbey Island, Wash., 

 X.L.G.. Nos. 81!, 918! 



We have commented on the relationships of this form and ou 

 the difficulty of distinguishing it, under the preceding form. 

 Yendo says (1902, p. 717) that it is difficult to give a sharp defi- 

 nition. In its most characteristic form, it is a thinner species 

 with sharper auricles to the joints in the type of the form, slender 

 stipe, etc., but all these vary and pass directly into the preceding 



