158 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



and must be considered as the type ; other forms found with us 

 are as follows : 



Var. ACICULARE (A. Br.) Hansgirg, 1886, p. 118; R. poly- 

 morphum var. aciculare Wolle, 1887, p. 197, PI. CLX, figs. 22 



and 23 ; R. aciculare Wittr., Nordst. and L,agerh., Alg. Exsicc., 

 No. 1243. Very slender, 1.5-3 /* diam., 15-20 diam. long, 

 acicular, straight or slightly curved, usually solitary. Mass., 

 Pa., Neb. Europe. 



Var. FUSIFORME (Corda) Hansgirg, 1886, p. 119; R. fascicu- 

 latum Nageli, 1848, p. 82, PI. IV. C, fig. i; P. B.-A., No. 

 1512. Fusiform, gradually tapering to each end; diam. 2-6 p., 

 cells 12-20 diam. long, straight or more or less curved, fascicu- 

 lately clustered. Fig. 42. Mass., Pa. Europe. 



2. R. CONVOLUTUM (Corda) Rabenhorst, 1868, p. 46 ; Wolle, 

 1887, p. 198, PL CL,X, figs. 1-5. Cells variously curved, con- 

 volute or contorted, 3.5-5 p- diam., 3-12 diam. long, ends obtuse 

 or apiculate ; cells usually solitary. Me., Mass., Pa., Neb. 



Europe. 



3. R. BRAUNII Nageli in Kiitzing, 1849, p. 891 ; Wolle, 

 1887, p. 198, PI. CLX, figs. 26 and 27; Wittr., Nordst. and 

 L,agerh., Alg. Exsicc., No. 1245. Cells cyclindric-fusiform, 

 relatively short and stout, 5-8 ^ diam., 4-6 diam. long, straight 

 or somewhat curved, slightly tapering at both ends, subobtuse ; 

 solitary or in pairs, rarely 3 or 4 together. Mass., Pa. Europe. 



4. R. SETIGERUM (Schroder) W. and G. S. West, 1901, p. 

 122. Rcinschiclla f sctigera Schroder, 1897, p. 489. Cells fusi- 

 form, the apices attenuate into long, fine setae. Diam. 3-6 /u. ; 

 length 60-85 /A ; chromatophore with one pyrenoid. Mass. 



Europe. 



R. FRACTUM W. and G. S. West, 1899, p. 279, from Domin- 

 ica, is described as near to R. Braunii, but somewhat narrower ; 

 the special character given is the division of the chromatophore 

 into four subequal parts. As the description was made from 

 dried specimens, it is not impossible that this appearance is due 

 to the preparation for cell division, in which case the distinction 

 from R. Braunii would not be clear. 



3. PALMELLOCOCCUS Chodat, 1894, p. 429. 



Cells free, globose, with wall of two or more layers, with one 

 or more disk-shaped chromatophores without pyrenoid, often 

 concealed by an orange-red coloring ; asexual reproduction by 

 bipartition of the cell, also by division into numerous aplano- 

 spores, which escape in a gelatinous vesicle. 



