ii2 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



15. S. ORTHOSPIRA Nageli in Kiitzing, 1849, p. 441 ; Petit, 

 1880, p. 30, PI. X, figs. 4 and 5 ; Wolle, 1887, p. 218, PI. 

 CXXXVI, figs. 10-11; S. majusacla P. B.-A., No. 511. Fila- 

 ments 60-66 /LI diam., cells 2-3 diam. long ; chromatophores 7 or 

 8, very slender, pale green, usually straight and parallel, some- 

 times inclined and making a quarter turn in the cell ; fertile 

 cells little or not at all swollen ; spores at maturity brown, len- 

 ticular, about 72 /j. diam., by 48 /A thick. Mass., N. Y., Pa., 

 Minn., Dakota. Europe, So. America. 



Usually in scattered filaments among other algae ; while in 

 each of its characters it resembles some other species, there is 

 no one which combines the characters of numerous, slender, 

 straight or nearly straight chromatophores, and lenticular 

 spores, not over 72 ^ diam. As No. 285 of Tilden, American 

 Algae, is distributed, under the name of 6*. majuscula var. brachy- 

 mcrcs, a plant agreeing with 6". orthospira, except that the cells 

 are somewhat larger. No spores were found in the specimen 

 examined, and it seems safer to include it under the type of the 

 species. 



16. S. MAXIMA (Hass.) Wittrock, 1882, p. 57; Wolle, 1887, 

 p. 218, PL CXXXIX, figs. 3 and 4; P. B.-A., No. 512; S. 

 oi-biculai-is Petit, 1880, p. 31, PI. XII, figs, i and 2; P. B.-A., 

 No. 1018. Filaments 130-140 /A diam., occasionally as low- as 

 118 fj. ; cells as long as the diam. or slightly more or less ; chro- 

 matophores 6 or 7, narrow, pale, very finely dentate, with large 

 pyrenoids, making half or three-quarters of a turn in a cell ; fer- 

 tile cells not swollen ; spores lenticular, brown at maturity, 

 about 100-115 fji diam., by 77-84 //. thick. Pa., Cal. 



l^uropc, So. America. 



The size of the filaments given above is the usual dimension, 

 but considerably larger or smaller are found, in exceptional 

 cases ; the American specimens seem to be usually smaller than 

 the European. 



Var. INAEOUALIS Wolle in Wittr. and Nordst., Alg. Exsicc., 

 No. 541 ; 1887, p. 218, PI. CXXXVIII, figs. 5 and 6. Sporif- 

 erous filaments about So p. diam., conjugating with filaments 

 about 125 fj- diam., spores not wider than the cells in which 

 they occur. Pa. 



Wittrock and Nordstedt suggest, Fasc. 21, p. 31, that this is 

 possibly a hybridization of two species. 



17. vS. CRASSA Kiitzing, 1843, p. 280, PI. XIV, fig. 4; 



