NO. 1 TAYLOR : PACIFIC MARINE ALGAE 207 



Mexico: Is. Revilla Gigedo, dredged from 56-102 meters' depth at 

 sta. 921 near I. Clarion, no. 39-38A, 17 Mar. 1939. Ibid., dredged at 

 sta. 129 from 25-32 meters' depth at Braithwaite Bay, I. Soccoro, no. 34- 

 14 (tetrasporic), 3 Jan. 1934. Ibid., from 41-84 meters' depth at sta. 

 924, no. 39-66, 18 Mar. 1939. 



PACHYMENIA J. Agardh, 1876 



Thallus foliaceous, simple or irregularly lobed, rather thick and 

 fleshy; medulla thick, of slender filaments and rhizoids, the inner cortex 

 loose, the larger cells with rhizoids interspersed, the outer cortex rather 

 thick, of anticlinal rows of small cells; tetrasporangia scattered; cysto- 

 carps scattered, small, in the inner cortex and medulla, with a prominent 

 spongy filamentous pericarp. 



Pachymenia saxicola n. sp.^^s 

 Plate 65, Figs. 1, 2 



Plants spreading to 7.5 cm from the holdfast, which is irregular, 0.5- 

 1.0 cm diam., the blade sessile or a little peltate, appressed to the substrate, 

 very firm in texture but the surface slipper}^, in the middle about 2 mm 

 thick (soaked up), dull reddish purple; shape irregular, near the base 

 broad, to 4-6 cm or more, or irregularly cleft and the widest branches only 

 about 2 cm, from the margins of the outer segments very irregularly 

 alternately branched and often closely beset with small ligulate prolifera- 

 tions; structurally showing a medulla of closely placed, elongated thick- 

 walled cells in filaments, and an inner cortex of irregular large rounded 

 cells with abundant filaments in the interstices; median cortex of large 

 rounded cells with thick walls grading externally to a layer about 85 /a 

 thick composed of anticlinal filaments once or twice branched, closely 

 placed, with thin walls, about 3 /a diam. near the surface and the cells 

 rather elongate, to 1-4 diameters; tetrapartite sporangia formed near the 

 inner part of the outer cortex but extending nearly to the surface at 

 maturity, large, oval, to 15-25 /a diam., 55-80 /x long. 



123 Pachymenia saxicola n. sp.— Plantae ad 7.5 cm, e haptero 0.5-1.0 cm diam. 

 orientes, sessiles aut subpeltatae, appressae, firmae sed lubricae, (madefactae) ad 

 2 mm crassitudine; forma irregulares, lobis ad basim 4-6 cm latitudine, aut in 

 segmenta ad 2 cm lat. fissis, marginibus externis irregulariter ramosis et saepe 

 ligulato-proliferis; tetrasporangiis ovatis, 15-25 !i diam., 55-80 u long. Planta 

 typica in loco dicto I. Santa Maria, Ecuador, legit W. R. Taylor no. 34-2d6, 18 

 Jan. 1934. 



