Ulothrix 147 



in its original sense, viz., for the species now recognized under 

 Urospora. * 



Hormiscia in this sense is distinguished from the marine 

 species of Ulothrix by the larger size of its filaments, the chroma- 

 tophore consisting of a more or less spiral band or of a somewhat 

 reticular parietal plate, and above all by the zoospores which are 

 narrowed at the posterior end into a pointed tail-like process. 

 This genus (as Urospora) has been removed to the Cladophoraceae 

 by Wille ('90), on account of the multinucleate character of the 

 cells, and therefore does not receive detailed treatment here. 



Synopsis of Species 



Fresh-water species. 



Filaments H-45 P m diameter, pyrenoids several. 



Mature filaments 25-45// in diameter. I. U. zonata. 



Cells 15-20// in diameter, y z as long. 2. U tenuissima. 



Cells 13-16 fi in diameter, 1-2 times as long. 3. U aequalis. 



Cells 11// in diameter, %-% as long. 4. U. oscillarina. 

 Filaments 5-9 // in diameter, one pyrenoid in a cell. 



Cells 7.5-9 y" in diameter. 5. U. tenerrima. 



Cells 5-6 // in diameter. 6. U. variabilis. 

 Salt or brackish-water species. 



Diameter 6-15 //, cell-wall thin. 7. U. implexa. 



Diameter 10-25 //, cell-wall thickened. 8. U.flacca. 



i. Ulothrix zonata (Web. & Mohr) Kutz. Flora, 16 : 519 

 1833 ; Phyc. Gen. 251.//. 80. 1843 J Spec. Alg. 347. 1849 

 Tab. Phyc. i\pl. go. f. 2. 1852. Dodel, Jahrb. wissen. Bot 

 10: 417-450. pi. 31-38. 1876. Wolle, F. W. Alg. 133.pl 

 ny. 1887. Chodat, Beitr. Krypt. Flor. Schweiz, I 3 : 267 

 / 183. 1902. 



*The North American species, then, are as follows : 



1. Hormiscia penicilliformis (Roth) Fries, Flor. Scan. 327. 1835. 

 Conferva penicilliformis Roth, Cat. Bot. 3 : 271. 1806. 



Urospora mirabilis Aresch. Nov. Act. Reg. Sci. Upsal. III. 6' : No. 2, p. 16. 

 1866. 



Urospora penicilliformis Aresch. Nov. Act. Reg. Sci. Upsal. III. 9 1 : No. I, p. 

 4. 1874. 



2. Hormiscia Wormskioldii (Fl. Dan.) Fries, /. c. 328. 

 Conferva Wormskioldii Fl. Dan. //. 1547. 1816. 



Urospora Wormskioldii Rosenvinge, Bot. Tidssk. 18: 57.64. 1892. 



3. Hormiscia collabens (Ag.) Rabenh. Deutsch. Krypt. Flor. 2 2 : 115. 1847. 

 Conferva collabens Ag. Syst. Alg. 102. 1824. 



Hormotrichum collabens Kutz. Phyc. German. 205. 1 845. 



