112 University of California Publications in Botany [you 8 



times many cells long (pi. 7, fig. 27). One cell at the end of the 

 loop divides lengthwnse, cutting off a cell which becomes the basal cell 

 of a branch which develops toward the surface, giving the appearance 

 of dichotomous branching, although virtualh' a single filament gives 

 rise to a single lateral branch at certain intervals. Occasionally after 

 the cortical portion of the thallus becomes dense, branches develop 

 without the formation of loops (pi. 7, fig. 28). This is in reality 

 true branching, for the erect filament is connately joined to the parent 

 filament. Soon a heterocyst is formed near the base of the erect 

 branch and eventually the upper part develops into a Calothrix-Yike 

 filament tapering to a yery delicate, hair-like point. Other intercalary 

 heterocj^sts may appear. These masses of erect parallel filaments form 

 the cortical portion of the thallus. 



The branching in Brachytrichia is similar to that of Mastigocoleus, 

 Nostochopsis and Herpyxonema. The trichomes in the last mentioned 

 genus have branches (cf. Weber-van Bosse, 1913, pp. 36, 37) with 

 V-shaped bases, and seemingly must arise exactly as do those in 

 Brachytrichia. We feel certain that these are true branches and that 

 the genus is closel}^ related to Brachytrichia, differing in lack of hairs 

 and in not forming a gelatinous thallus. 



Brachytrichia affinis S. and G. 

 Plate 7, figs. 27, 28 



Thallus small, 0.5-2 cm. diam., deeply plicate, bullate, cavernous, 

 cartilaginous, light blue-green, or brownish with age ; filaments intri- 

 cate, loosely intertwined below, very densely crowded and parallel 

 above, and tapering gradually into delicate hairs ; cells of the lower 

 interior filaments slightly ventricose, 4—5fi diam., 1.5-2 times as long 

 as broad; cells of the erect filaments spherical to doliiform toward 

 the base, 1-9 fx. diam., terminal cells Ifx diam. ; heterocysts spherical or 

 slightly compressed. 



Growing in rock pools in the middle littoral belt. Laguna Beach, 

 Orange County, California. 



Setchell and Gardner, in Gardner, New Pac. Coast Alg. Ill, 1918a, 

 p. 475, pi. 41, figs. 27, 28. Brachytrichia Qiwyi Guernsey, Notes on 

 Mar. Alg., 1912, p. 195; Collins, Holden and Setchell, Phyc. Bor.- 

 Amer. (Exsicc), no. 2106 type (not of Bornet and Flahault). 



Brachytrichia Quoyi was accredited to our coast by Bornet and 

 Flahault (Rev. II, 1886, p. 373) on the authority of Grunow, but 



