146 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 17 



to the east of the town, but was not found at all on the rocky shore a 

 few miles west on the other side of the town. It is not a tidepool plant, 

 but grows over all surfaces of rocks subject to heavy surf. 



This species is similar to Amphiroa zonata Yendo in form, branching 

 and in zonal markings of terminal parts. The short intergenicula and 

 more prominent genicula are distinctive, however, and the plant is more 

 fragile when dry. 



Amphiroa zonata Yendo 



Yendo, 1902a, p. 10, pi. 1, figs. 11-14, pi. 4, fig. 9; Dawson, 1944, 

 p. 276. Amphiroa peninsularis Taylor, 1945, p. 188, pi. 48, fig. 1 ; Daw- 

 son, 1949, p. 228; Dawson, 1951, p. 53. Amphiroa pusilla Yendo, as 

 interpreted by Dawson, 1944, p. 276, in part. Amphiroa compressa var. 

 tenuis Taylor, 1945, p. 191, pi. 53, fig. 1. 



Thalli saxicolous, moderately calcified, erect, loosely or sometimes 

 rather densely tufted, 3-6, or to 10 cm. high, regularly to irregularly 

 dichotomously branched more or less in one plane, or sometimes with a 

 tendency to being decussate; segments smooth, the younger ones with 

 prominent annular markings, cylindrical, or more or less prominently 

 compressed in part or throughout, especially at the forks, of more or less 

 uniform diameter throughout a given plant, 0.7-1.2 mm. in diameter, or 

 sometimes as slender as 0.45-0.6 mm., of irregular length, mostly over 

 10 diameters long, at least above, and sometimes up to 20 diameters 

 long; apices truncate, in dry specimens usually with a distinct narrow 

 constriction just below the apex ; genicula irregularly placed with respect 

 to forkings so that intergenicula may be simple or forked (when forked 

 the limbs often of different lengths), multizonal, usually of 3 cell-tiers 

 in upper parts; intergenicula commonly with a thin cortex of 1-4 layers 

 of very small cells, thicker in age, with a medulla usually showing 3-4 

 tiers of long cells alternating with a zone of very short cells ; tetrasporic 

 conceptacles numerous below, 350-500 ix. in diameter, slightly elevated, 

 often producing bispores ; sexual conceptacles not identified. 



Type: Holotype not designated and no type material found in 

 Yendo's herbarium in the Botanical Institute, Tokyo University in 1951. 



Type locality: None specifically designated but the Japanese 

 localities of Misaki, Shimoda and Sunosaki indicated. 



Distribution: This species has now proved to be a common one 

 along much of the northern Pacific Mexican coast and extends north into 

 southern California. Along Pacific Baja California and in southern Cali- 



