NO. 10 DAWSON : MARINE ALGAE, GULF OF CALIFORNIA 221 



pusillus group of Sauvageau (1895). Both species differ from all others 

 recognized by Setchell and Gardner in the method of branching and in 

 the lack of hairs terminating the erect filaments. 



Bryant 3a, growing on Crjdium simulans. La Paz. Not again detected. 



Ectocarpus gonodioides S. & G. 



Setch. & Gard., 1924, p. 721, pi. 17, fig. 44. 



According to Setchell and Gardner, the small tufts of this species re- 

 mind one of the genus Gonodia (Myriactis), but the penetrating part, 

 which extends relatively deeply into the host, is composed of slender, al- 

 most colorless, slightly branched, closely intertwined filaments, which, 

 however, do not coalesce or form a false parenchyma as in the case of some 

 species of Gonodia. 



J. 47e, growing on Codium cuneatum. Smith Island, July. Not again 

 detected. 



Ectocarpus sonorensis sp. nov. 

 Plate 31, Fig. 5 



Frondes usque ad 10 cm. altae; fills priraariis usque ad 50 \x, diam., cellulis 1.25- 

 1.50-pIo diam. longioribus; ramificatione semierecta, moderate remota ; ramulis 

 superne usque ad 12 \i attenuatis; ramis ultimis usque ad apicem acutam elongato- 

 subulatis; rameliis spinuliformibus superne nurnerosis; gametangiis piuril'x:ulari- 

 bus gracilibus, usque ad 400 n longis, 20-25 \x latis, in extensionem cellularura vege- 

 tatlvarum terminantibus, pedicellis 2-ceIlularibuB suffultis. 



Plants large, light green abundantly and finely branched, to 10 cm. 

 high; main filaments up to 50 jj. in diam., of thin-walled cells 1.25-1.5 

 times as long as broad ; branching semi-erect, rather distant; ramuli grad- 

 ually attenuating from 40 /a to 12 /x diam., ultimate branches elongate- 

 subulate, to a sharp point, in terminal parts bearing numerous short, spine- 

 like ramelli ; chloroplasts pale, thin, nongranular, apparently lining the 

 walls; plurilocular gametangia developing in same position and orienta- 

 tion as short vegetative branches of upper parts of the plant, uniformly 

 borne on a 2-celled pedicel, slender, to 400 ix long, 20-25 /a wide, ending 

 in a pointed extension of vegetative cells 30-120 fi long; zoosporangia un- 

 known. 



Type: D. & R. 3281 (Field Museum, Chicago; isotype, AHF no. 

 7), on rocks m tidal stream, 3 km. east of Guaymas, December 15, 1939. 



Its large size and branching habit, together with the peculiarities of 

 its plurilocular gametangia, identify this species as a very distinctive one 

 from our coasts. 



