THE GREEN ALGAE OF NORTH AMERICA 29 



(Wolle) De Toni, 1889, p. 622 ; Hydrianum subsessile Wolle, 

 18773 p. 186 ; and C. giganteum (Wolle) De Toni, 1889, p. 624 ; 

 Hydrianum giganteum Wolle, 18773, p. 186, but descriptions 

 are too unsatisfactory for recognition. 



Page 157, for Key to the Species of Rhaphidium, substitute, 



KEY TO THE SPECIES OF ANKISTRODESMUS. 



i. Cells or colonies in gelatinous sheath. 5. A. lacustris. 



i. No gelatinous sheath. 2. 



2. Cells fusiform, ending in long bristles. 4. A. setigerus. 



2. No bristles. 3. 



3. Cells much twisted. 2. A. convolutus. 



3. Cells straight or curved, not twisted. 4. 



4. Cells slender, fusiform to acicular, straight, sigmoid or somewhat 



lunate, gradually tapering to a fine point. i. A.falcatus. 



4. Cells stouter. 5. 



5. Cells subcylindrical, usually straight, short-pointed. 



3. A. Braunii. 



5. Cells more or less lunate with acute apices; chromatophore with 

 central notch and 2 pyrenoids. 6. A. Chodati. 



Page 158, after description of R. SETIGERUM, note, 



G. M. Smith, 1916, p. 473, PI. XXIV, fig. 8, removes this 

 species to the genus Schroederia as 6". setigera (Schroder) Lem- 

 mermann, 1898, p. 311, and describes a new species, S.Judayi 

 G. M. Smith, 1916, p. 474, PI. XXIV, figs. 9-11. Cells fusi- 

 form, straight or curved, ends attenuate into hair-like projec- 

 tions, one of which terminates in a disk ; chromatophore single, 

 parietal, with one pyrenoid. Length with spines, 45-63 n, 

 without spines, 14-30 /* ; breadth 6-25 /*. Wis., G. M. Smith. 



The genus SCHROEDERIA was separated from ANKISTRODES- 

 MUS by Lemmermann on account of the much prolonged apices, 

 but has not generally been accepted. G. M. Smith figures a 

 terminal disk in >S. setigera, as well as in S. Judayi. If this is 

 really a generic character, it may raise some questions as to the 

 affinities of the genus. 



5. A. LACUSTRIS (Chodat) Ostenfeld, 1907, p. 384 ; Raphi- 

 dium Braunii var. lacustris Chodat, 1902, p. 200, fig. 117. Cells 

 scattered without order in the gelatinous sheath, fusiform, 

 18-37 X 4 p, straight or somewhat curved, ends usually acute. 

 Wis., G. M. Smith. Europe. 



6. A. CHODATI (Tanner) Brunnthaler in Pascher, 1915, 

 P- r 93> fig- 36 5 Raphidium Chodati Tanner-Fullemann, 1906, 



