THE GREEN ALGAE OF NORTH AMERICA 295 



2. M. STRICTISSIMUM Rabenhorst, Algen, No. 829; Ha/en, 

 1902, p. 191, PI. XXYI, figs. 2-5; P. B.-A., No. 1425. Up to 

 600 /u. tall, erect, branching mostly alternate, the main stems dis- 

 tinguishable throughout ; branches erect or ascending ; cells 

 cylindrical, 2.5-4 p. cliam., about the same size all through the 

 frond, 3-12 diain. long, or even more; chromatophore thin, pale 

 green, often only partially covering the wall. Conn., N. Y. 



l^urope, So. America. 



In similar stations to the preceding species ; distinguished by 

 the greater size, longer articulations, and different ramification. 



Yar. MACROCYSTIS Schmidle, 1899, p. 169, Tl. VII, figs. 1-3; 

 Hazen, 1902, p. 192, PI. XXVII, fig. i. Taller, branching 

 more open ; branches more slender than main stem, somewhat 

 tapering ; chromatophore pale and narrow ; tips of branches 

 colorless. Mass., N. Y. Europe. 



Found growing on dead leaves in a rain water ditch. 

 23. CHAETOPHORA Schrank, 1813, p. 124. 



Filaments arising from a palmelloid base, and united by a firm 

 gelatinous substance into thalli of definite form ; filaments re- 

 peatedly branched, of about the same diameter throughout, 

 ramuli often in fascicles, frequently terminating in long setae. 

 Chromatophore a parietal band with one or more pyrenoids. 

 Asexual reproduction by biciliate zoospores, formed in the cells 

 of the ramuli ; akinetes from any cell. 



The filaments are much like those of Stigeoclonium , but the 

 branching has more of a dichotomous appearance ; the whole is 

 imbedded in a gelatinous mass of definite form, spherical, tuber- 

 cular, or elongate and branching. The plants are attached to 

 sticks, stones, etc., and are common in clear running water in 

 spring ; less common in quiet water. 



KEY TO THE SPECIES OF CHAETOPHORA. 



r. Thalli elongate, lobed and branching. 4. C. incrassata. 



i. Thalli globose or tuberculose. 2. 



2. Branching loose and spreading. i. C. elegans. 



2. Branching erect. 3. 



3. Branches fascicled at the summit. 2. C. pisifor^is. 



3. Branches not fascicled at the summit. 3. C. attenuata. 



i. C. ELEGANS (Roth) Agardh, 1812, p. 42; Wolle, 1887, 

 p. 116, PL CIII, fig. 4-10 ; Hazen, 1902, p. 211, PI. XXXVII; 

 P. B.-A., No. 1026. Thalli globose or oftener tuberculose, up 

 to i cm. diam, light green, rather soft ; filaments radiating from 

 the center, di-trichotomously branched and fasciculate above ; 



