GYMXOZYGA. 255 



Jacobs. Desm. Dane in. 1875, p. 213. 



Hansg. Prodr. Alg. Bohm. 1888, p. 169. 



De Toni. Syll. Alg. 1889, p. 797. 



U'ille in Engler Xatur. Pflanzenfam. 1890, p. 15. 



G. S. West, Brit. Freshw. Alg. 1904, p. 178. 



Bambusina Kiitz. Phyc. germ. 1845, p. 140 ; Spec. Alg. 1849, p. 188. 



De Bary, Conj. 1858, p. 76. 



Rabenh. Flor. Eur. Alg. 1868, p. 152. 



Delp. Desm. subalp. 1877, p. 54. 



Kin-hn. A1-. Sc-hles. 1878, p. 132. 



\Volle, Desm. I". S. 1S84, p. 24. 



Cooke, Brit. Desm. 1887, p. 8 



Comere, Desm. France, 1901, p. 197. 



Cells cylindrical or barrel-shaped, united by their flat 

 ends to form slightly twisted filaments. There is a 

 very slight median constriction, and often a swelling 

 of variable size at the base of each semicell. Vertical 

 view circular, often with two opposite mamillse. Cell- 

 division similar to that of Desmidhini. 



Zygospore smooth, oval or subglobose. 



The genus Gymnozyga is very closely related to Desmidium, 

 and it has beeD -uggested by many previous authors that the 

 two genera should be united. However, the distinctive characters 

 of its form, the elongated barrel-shaped cells and the entire 

 absence of a distinct median incision, both characters which 

 contrast strongly with I)rs,,i'u1i '/////. seem to justify the retention 

 of Gymnozyga. 



There is only one British species of the genus. 



1. Gymnozyga moniliformis Ehrenb. 

 (PL CLXV, figs. 8, 9.) 



Gynn>i>:i/'/n iitoHilifttrini* Khiviib. in Berlin Monatsb. 1841, p. 212 : Xordst. 



Bornh! Drsm. 1888, p. 20!> ; De Toni. Syll. Alg. 1889, p. 797 ; West, Alg. W. 



Jivlancl. 1S!2. ]>. 117 : Alg. Kngl. Lake Distr. 1892, p. 7 : Turn. Freshw. 



Alt:. K. India, 1893. p. 151 : JJoy \- Biss. Scott. Desm. 1893, p. 10 ; West 



& G. S. West, A1-. S. England, 1897, p. 497 ; Alga-fl. Yorks. 1901, p. Ill ; 



\\VI\v. Airie. Alg" 1897, p. 53 ; Alg. X. Ireland, 1902, p. 60 ; Alg. Burma, 



1<M7. p. 22(3; Fritt-h. Alg. Ceylon, 1907, p. 237, f . 3, K ; Bernard, 



AL f . imicell. domaine Malais, 1909, p. 23, t. 1, f. 19 ; Borge, Sao Paulo 



Siisswasseralg. 1918, p. 77. 

 Desiiiiiliinit Borreri Ralfs in Ann. Mag. Xat. Hist. 1843, ii, p. 375, t. 8, f. 4 ; 



Mass. Brit. Freshw. Alg. 1845, p. 343, t. 83, f. 9, 10. 

 Bambusina Brebissonii Kiitz. Phyc. germ, 1845, p. 140; Spec. Alg. 1849, 



p. 188 ; De Bary, Conj. 1858, p. 76, t, 4, f. 28, 29 ; Rabenh. Flor. Eur. 



Ala. 1868, p. 153 ; Kirchn. Alg. Schles. 1878, p. 132 ; Wolle, Desm. U.S. 



1884, p. 24, t. 1, f. 15-21 (?) : Cooke, Brit. Desm. 1887, p. 9, t. 4, f. 1 ; 



Hauptfl. Zellm. Htillgallerte Desm. 1888, pp. 13, 56 ; t. 1, f. 19-21, 24, 



25, 31-38. 

 Didymoprium Borreri Ralfs in Ami. Mag. Nat. Hist, xvi, 1845. p. 10, t. 3,.. 



