i8 TUFTS COLLEGE STUDIES, VOL. IV, No. 7 



62. S. ikKKt.i LAKIS Nageli in Kiit/ing, 1849, p. 440; 

 18553, p. 7, PI. XXII, fig. n. Pale or dirty green, little lu- 

 bricous; vegetative cells cylindrical, 32-36 /* diam., 3^2-7 diain. 

 long ; dissepiments plane ; fertile cells scarcely swollen ; chro- 

 matophores 2-3, very slender, with large, nodulose, distant 

 pyrenoids, making three-fourths to one turn in a cell ; spores 

 32-36 /* diam., i%-2 diam. long. Charleston, 111., Trauseau. 



Europe. 



Spirogyra gigantica Grace A. Hill, 1916, p. 198, is founded 

 on a sterile plant resembling 5". crassa, but with somewhat 

 larger filaments, 173-188 p. against 150-160; chromatophores 

 making more turns to the cell ; pyrenoids somewhat larger. 

 The dimensions of 5". crassa are probably taken from Collins, 

 '99. P- "3. but M I SS HM apparently overlooked p. 105 of the 

 same paper. " Specific distinctions not always clear, based on 

 the character of the dissepiments, the number and breadth of 

 the chromatophores, the size and form of the spore, the charac- 

 ter of its median membrane, the inflation of the fertile cell, and, 

 too often, the dimensions of the filaments ; this last character 

 being too uncertain to have much weight, except when asso- 

 ciated uniformly with other characters." 



The specific name proposed appears to sin against the inter 

 national rules of botanical nomenclature, Chapter I, Art. 7. 

 "Scientific names are in Latin for all groups." Gigantfus is 

 good Latin, and has frequently been used as a specific name : 

 there appears to be no authority for giganticus. 



Page 119, cancel all under DEBARYA, and substitute, 



DEBARYA Wittrock, 1872, p. 35. 



Cells cylindrical, or contracted at the dissepiments; chro- 

 matophores either several, stellate, each with one pyrenoid, or 

 a single axial plate with several pyrenoids ; conjugation be- 

 tween two filaments not differing in appearance, the entire con- 

 tents of the conjugating cells (gametangia) passing into the 

 tube to form the zygospore ; gametangia not walled off from 

 the spore, but filling up with cellulose. 



KEY TO THR SPKCIRS OP DRBARYA. 

 i. Spore* with longitudinal line* ami crow ridge*. 



i. D. gtyptospcrm*. 

 i. Spores verrncote or scrobiculate, without line*. a. 



