138 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 17 



Amphiroa taylorii sp. nov. 

 Plate 26, fig. 1 



Amphiroa annulata Lemoine, as interpreted by Taylor, 1945, p, 188, 

 with regard to Socorro Island material only. 



Thallis laxe rosulatis vel intertextis, ad 1.3 cm. altis, ubique cy- 

 lindricis, at diametri irregularis (250-450 /*) in partibus diversis, infra 

 irregulariter multifarie pinnateve ramificatis, supra baud ramificatis vel 

 exigue dichotomis, ramis in partes diversas curvatis, pauIo attenuatis; 

 segmentis variis longitudine, 2-15 (plerumque 6) diametris longis, maius 

 calcificatis, ad genicula constrictis; cortice intergeniculari crassa. 



Thalli loosely tufted or matted, growing on crustose corallines with 

 other small, mat-forming algae, to 1.3 cm. high, consisting of many erect, 

 sparsely branched axes from a spreading, crustose stratum; erect axes 

 250-450 /A in diameter, strictly cylindrical but of irregular diameter in 

 various parts, unbranched above or occasionally dichotomously branched, 

 frequently irregularly, multifariously, or pinnately branched below, the 

 branches mostly not straight, but curved in various directions, generally 

 somewhat attenuated but terminally blunt or truncate ; segments of vari- 

 able length, 2-15 diameters long, mostly more than 6 diameters long, 

 usually rather heavily calcified, with annulations inconspicuous except 

 in young parts, prominently constricted at the genicula which are about 

 half as broad as the intergenicula or less; genicula usually of two cell 

 tiers; intergenicular cortex rather thick except in very young parts, of 

 6-8 or more layers of small cells, becoming very thick in age by secondary 

 growth ; fertile branches appearing variously swollen and distorted from 

 the irregular bulges caused by the immersed conceptacles and from un- 

 even secondary growth of the cortex, the ostiole inconspicuous and close- 

 ed early by the heavy calcification; tetrasporangial conceptacles im- 

 mersed, causing prominent bulges on the surface, 200-250 \i in diameter, 

 about 150 /i high; antheridial conceptacles more or less completely im- 

 mersed, causing only slight surface prominence, about 175 /a broad, 100 /a 

 high, the cavity much flattened ; carposporic plants not seen. 



Type: Holotype is Taylor 34-27, Jan. 2, 1934, in box 3633 and 

 on slides 1462-1463 in HAHF. 



Type locality: On littoral rocks, Bahia Braithwaite, Isla So- 

 corro. Revillagigedo Archipelago, Mexico. 



Additional material: Dawson 3383 (Nov.), D. 6833 (Mar.), 

 Cabeza Ballena, Baja Calif.; Taylor 39-666, dredged from 5-9 meters, 

 Isla Maria Magdalena, Nayarit, May. 



