88 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 12 



4. Plants dark brown, firm D. Binghamiae 



4. Plants more delicate and lighter in color, appearing alternately 

 branched above D- flabellata 



5. Plants entangled, the lower segments moderately broad but the 

 upper nearly filiform, the angles very wide, commonly over 90° 

 D. divaricata 



5. Plants without extraordinary reduction in branch width or par- 

 ticularly divergent branching 6 



6. Branching closely dichotomous, at narrow angles, the segments 

 oblong to cuneate D. Vivesii 



6. Branching often subpalmate, especially above, the segments short 

 and broad ; the branches often becoming attached to each other 

 D. concrescens 



Dictyota Binghamiae J. Agardh 



Setchell & Gardner 1925, p. 652, pi. 34, figs. 1, 2. 



Mexico: Baja California, intertidal at Point Hughes on Cabo San 

 Lazaro, no. 34-599, 7 Mar. 1934. Ibid., Ba. Thurloe, Pto. San Bartol- 

 ome, no. 34-613, 9 Mar. 1934. Panama: dredged from 21 meters' 

 depth off Is. Secas, Schmitt no. 456C-35, 6 Feb. 1935. 



Dictyota flabellata (Collins) Setchell & Gardner 

 Collins in Phyc. Bor.-Amer. no. 834; Setchell & Gardner 1925, p. 

 652, pi. 34, fig. 3; Smith 1944, p. 101, pi. 15, fig. 6. 



These specimens seem rather thin for this species, but are interpreted 

 as deep-water forms, juvenile and still mostly in the dichotomous growth 

 phase. The species was originally placed in the genus Dilophus, but it 

 appears more difficult to distinguish Dilophus from Dictyota in the Pacific 

 flora than in the Caribbean. The writer follows Setchell and Gardner 

 in this instance. 



Costa Rica: Dredged off Pto. Culebra, no. 34-258 (sexual plants) 

 24 Feb. 1934. Panama: Dredged from 21 meters' depth off Is. Secas, 

 Schmitt no. 456B-35, 6 Feb. 1935. 



Dictyota major n. sp.®^ 

 Plates 8, 9 



Plants to 40 cm tall, light brown, and delicate except near the base, 

 sparingly branched ; stalklike base narrow, gradually expanding to about 



65 Dictyota major n. sp.— Plantae ad 40 cm altitudine, delicatae, sparse dicho- 

 tomeque ramosae, ad 1 cm latitudine, furcatae intervallis 3-11 cm angulisque 

 angustatis, smu subcurvato; marginibus integris, paulum sinuoso-curvatis. Planta 

 typica in loco dicto Post Office Bay, I. Santa Maria, Ecuador, legit W. R. Taylor 

 no. 34-357, 27 Jan. 1934. 



