88 NEMALIONACEAE 
are truly erect. Its sporangia are larger than those of A. clan- 
estinum and are commonly larger than the supporting cells. 
PLATE 31, FIGURES 19-24. Acrochaetium clandestinum 
19. A part of a basal disc with young erect filaments. 
20. Apical portion of a main branch of a mature erect filament, showing secund 
ultimate ramuli, monosporangia, chromatophores, etc. 
+ + š . +. > за. is thin-walled 
21. А rangia, 
lobed or divided chromatophores, position of pyrenoid, etc. 
22. A rather unusually elongate monosporangium with a one-celled pedicel. 
23. A portion of main axis, showing form of cells and chromatophores, position of the 
pyrenoid, empty sporangia, etc. 
24. А cell from the main axis, with chromatophore lobed in a more or less ribbon- 
aped fashion and the pyrenoid near the upper end. 
АП figures from plants on Chaetomorpha (La Punta, region of Callao, Coker 38 
р.р.). Figures 19 and 20 are enlarged 390 diameters; 21-24, 675 diameters. 
Acrochaetium polysporum sp. nov. 
Basal disc well developed, monostromatic, suborbicular, mostly 
150-850 и in diameter, closely adherent to the substratum, at 
first parenchymatous, later often irregularly filamentous at the 
margin, nearly all of the cells finally producing erect filaments; 
cells of the disc 5.5-8.0 и broad, 1-2 times as long; erect filaments 
very numerous, finally 300-500 и (20—40 cells) long, with few ог 
many of the intermingled and marginal remaining 25-80 и (2-6 
cells) long, all simple or in very rare cases, with a single vegetative 
branch, the cells cylindric or slightly tumid, 11-22 u X 8-11 M, 
1-3 times as long as wide; chromatophore parietal, usually more 
or less 2-lobed proximally and distally, often (especially before 
cell division) so deeply lobed as to appear H-shaped, or merely ` 
unilaterally cleft or irregularly and sparingly cribose, pyrenoid 
usually a little eccentric; sporangia ovoid, 16-24и X 8.5-12 № 
polysporous, containing usually 8-16 (—32?) spores, lateral ог 
terminal, mostly in a secund lateral series of 3-20, very rarely 
opposite, sessile or with a unicellular pedicel, nearly every cell of 
the erect filament sometimes giving rise to a sporangium, com- 
monly also terminal on the short and less commonly on the longer 
filaments, cells of the main filaments occasionally converted di- 
rectly into sporangia and then becoming more or less unilaterally 
gibbous or protuberant, the lateral and terminal sporangia often 
regenerated from below. [PLATE 31, FIGURES 1-11.) 
Growing on the laminae of Lessonia nigrescens, Pescadores | 
Islands, region of Ancón, Feb. 12, 1907, Coker 09150 Р.Р. (type); 
Chincha Islands, Coker 107 b.b.; also, rather poorly developed, on 
the leaves of Macrocystis integrifolia, Chincha Islands, Coker 00014: 
