28 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 17 



Thalli epiphytic, tufted, to 1 mm. high or more, arising from a base 

 of massed, creeping filaments ; erect filaments when well developed with 

 about 3 orders of branches in one plane, those of the first order sparse, 

 irregular, indeterminate; branchlets of the second and third orders abun- 

 dant, determinate, of 1-3 cells, mostly opposite, sometimes alternate or 

 secund; cells decreasing in size from base to apex of filaments, 7.0-9.0 

 fi in diameter at the apex of filaments and from 1.5-2 times as long, 10.0- 

 13.0 /A long; chromatophore apical and somewhat lobed; sexual repro- 

 duction unknown. 



Type: Holotype is Gardner 4441, April 1918, on sheet 294559 in 

 the Herbarium of the University of California, Berkeley. 



Type locality: Fort Point, San Francisco, California. 



Mexican distribution: Pacific Baja Calif. — D. 64-45, (in 

 Herb. U. C.) on old Rhodoglossum, Punta Descanso, Apr.; D. 78a, on 

 Egregia, Cabo Colnett, Jan.; D. 9169b, on Cystoseira, Bahia Asuncion, 

 Apr. 



Acrochaetium daviesii (Dillwyn) Nageli 



Nageli, 1861, p. 405, figs. 26-27; Hamel, 1928, p. 133, figs. 31a-g; 

 Kylin, 1944, p. 20, fig. 12; Taylor, 1945, p. 134. Conferva daviesii 

 Dillwyn, 1809, p. 73, pi. F. 



Thalli epiphytic, to 2 mm. high, consisting of a basal disc of closely 

 approximate creeping filaments from which arise erect, branched fila- 

 ments; erect filaments cylindrical, 9.0-12.0 /x in diam., of cells about 3 

 times as long as broad; branching irregular, alternate or secund, of 

 several orders; chromatophore band-shaped, parietal; asexual reproduc- 

 tion by monospores and tetraspores; monosporangia terminal and lateral 

 on short adaxial branchlets which form axilary clusters, 8-12 fi diam.; 

 tetrasporangia not seen in Mexican material. 



Type: Holotype not designated and whereabouts of syntypes un- 

 known to the writer. They are not among Dillwyn types at the Linnaean 

 Society, London. 



Type locality: Great Britain (plants from three localities used 

 in original description). 



Mexican distribution: Pacific Baja Calif. — D. 8482, on 

 old LiagorOj Isla Guadalupe, Dec; Hubbs 46-203, on old Cystophora, 

 Isla Guadalupe, Aug. Revillagigedo Archip. — Taylor 52, on Caulerpa, 

 Isla Clarion, Jan. 



