160 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 17 



Thallis 2.5-8 cm. altis, densius pinnate, irregulariter alternate op- 

 positeve ramificatis, saepe corymbosius; intergeniculis latissime cuneatis, 

 plerumque 2.5-3.0 mm. latis, .75-1.25 mm. longi's, 0.5-0.6 mm. crassis 

 ad costam indistinctam ; alis prominentibus, teretibus, truncatis vel 

 acutis. 



Thalli 2.5-8 cm. high, consisting of several erect, branched parts 

 from a crustose basal stratum; erect parts strongly compressed or flat- 

 tened except at the very base, rather densely pinnately, irregularly alter- 

 nately or oppositely branched, often somewhat corymbose, with only 

 occasional dichotomous branching above but sometimes frequent below, 

 often with many single-segment pinnae; intergenicula very broadly 

 cuneate, usually shaped like a wing nut, much broader than long (2.0) 

 2.5-3.0 (3.5) mm. broad, .75-1.25 (1.5) mm. long, 0.5-0.6 mm. 

 thick at the usually distinct midrib, with prominent, rounded, truncated 

 or sometimes acute wings, the edges of wings of adjoining intergenicula 

 often overlapping slightly; genicula unizonal, about 250 /i, long; inter- 

 genicular medulla of uniform zones of straight filaments; asexual con- 

 ceptacles domoid, 500-700 ju in diameter, irregularly arranged on flat- 

 tened surfaces of intergenicula, but usually one on either side of midrib, 

 often congested in older parts, bearing tetrasporangia or bisporangia, the 

 ostiole usually excentric; carposporic conceptacles rostrate, asymmetrical, 

 with the ostiole somewhat lateral; antheridial conceptacles 400-550 fi 

 in diameter, rostrate. 



Type: Holotype is Silva 6219, Mar. 15, 1950, in the Herbarium 

 of the University of California, Berkeley. An isotype is in HAHF. 



Type locality: Lower littoral rocks, Smugglers Cove, Santa 

 Cruz Island, Calif. 



Additional material: California — Silva 4203, Pelican Bay, 

 Santa Cruz Island, Jan.; Silva 3822, Willows Anchorage, Santa Cruz 

 Island, Jan.; Silva 4422, Santa Barbara Island, Feb.; Silva 3410, San 

 Clemente Island, Aug.; Silva 1516, San Miguel Island, Jan.; D. 1297, 

 La Jolla, Jan. Pacific Baja Calif.— Silva 4879, Feb., Hubbs 48-218, 

 Aug., Islas Los Coronados; D. 275, 8 km. south of Punta Descanso, 

 Jan.; D. 10281, mouth of Rio San Miguel, Aug.; Silva 1525, Islas 

 Todos Santos, Feb.; D. 8835, Jan., 1262, Apr., Punta Baja; D. 2764, 

 2765, Punta Santa Rosalia, Oct.; D. 9112b-c, Islas San Benito, Apr.; 

 Taylor 34-643a, Mar., D. 6543, Mar., D. 9848, 9859, Apr., South 

 Bay, Isla Cedros; D. 10405, Punta San Eugenio, Nov.; D. 9176, Bahia 

 Asuncion, Apr. 



