236 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 3 



Family Desmarestiaceae 



Genus DESMARESTIA Kjellm. 



Desmarestia filamentosa sp. nov. 

 Plate 76 



Frondibus cylindaceis, inferne lente compressis; stipitibus 1.5-2 mm. diam., 5 

 cm. usque ad laminam primam; ramis totaliter oppositis et copiosis, gradatim et 

 successive magnitudine decrescentibus; ramulis ultimis gracillimis flaccidisque, 80- 

 100 |x diam, ; corporibus reproductivis ignotis. 



Fronds cylindrical, or somewhat compressed in older parts, to 5 dm. 

 high, with profuse, opposite branching throughout, from a stipe about 5 

 cm. long below the first branches, pale greenish brown when dry; main 

 axis 1.5-2 mm. diam. with 4-5 orders of branches gradually reduced in 

 size, the ultimate ramuli very slender and flaccid, 80-110 ju diam., each 

 producing by trichothallic growth from its tip a slender, monosiphonous 

 hair of short, swollen cells about 40 /x, diam., in a catenate series; repro- 

 duction not seen. 



Type : Dredged in 15 fathoms, Puerto Refugio, Angel de la Guardia 

 Island, March 20, 1937. Herb. AHF no. 64. 



This species is similar in general form and structure to Desmarestia 

 media (Ag.) Grev. from Alaska and Puget Sound. It also resembles D. 

 compressa (Reinsch) Skottsberg from the Antarctic region. 



Desmarestia mexicana sp. nov. 

 Plate 77 



Frons membranacea, 9-15 dm. alta, ad 18 cm. lata, e disco simplici, 8-10 cm. 

 longe stipitata, simpliciuscula vel e stipite ramosa; frons e stipite cuneatim dilata, 

 simpliciuscula, costata, dentata. 



Fronds from a small discoid holdfast giving rise to a slender, com- 

 pressed, usually branched stipe 8-10 cm. long, 2-3 mm. wide, the several 

 branches expanding gradually into large, broad, thin, membranous blades 

 9-15 dm. long, up to 18 cm. wide, of a pale greenish brown color when 

 dry; blades unbranched, with a slender mid-vein from which opposite, 

 lateral veins branch at regular intervals, these breaking up into fine vein- 

 lets; margins with regularly spaced, broad, low teeth, the abruptly sharp 

 points directed upward ; blades commonly lacerate above, the apical parts 

 unknown. 



Type: Dredged in 15 fathoms, Puerto Refugio, Angel de la Guardia 

 Island, March 20, 1937. Herb. AHF no. 65. 



The two Desmarestia species here described from Puerto Refugio are 

 remarkable in being the southernmost representatives of the genus on our 



