84 ZYGOPHYCEA. 
The following is a tabular arrangement of the British species :— 
Sec. 1. Cells not replicate at the ends. 
A. Chlorophyll bands numerous (rarely two). 
* Spores ovoid or elliptic. 
+ Membrane smooth. 
1. crassa, Kz. 
2. jugalis, Dill. 
3. nitida, Lk. 
++ Membrane punctate. 
None. 
** Spores orbicular. 
+ Membrane smooth. 
4, orthospira, Nag. 
+t Membrane punctate. 
5. orbicularis, Hass. 
6. bellis, Hass. 
B. Chlorophyll bands single or double (rarely ternate). 
* Spore membrane smooth. 
7. porticalis, Vauch. 
var. a. quinina. 
Chlorophyll bands usually single. 
var. B. decimina. 
Chlorophyll bands usually binate, rarely ternate. 
var. ¢. rivularis, Hass. * 
Chlorophyll bands usnally three. 
#* Spore membrane punctate. 
None. 
N.B.—Spirogyra elongata, Berk. Glean., p. 33, tab. 12,f.3 (Rabh. 
Alg. iii, 241), would follow here but that the fruit is unknown, and hence 
it is uncertain. 
C. Chlorophyll bands single. 
* Spore membrane smooth. 
9. condensata, Vauch. 
9. longata, Vauch. 
10. flavescens, Cleve. 
** Spore membrane punctate. 
(N.B.—No record of Sp. velata or Sp. punctata in Britain.) 
Sec. 2. Cells replicate at the ends. 
A. Chlorophyll bands usually two or more. 
* Spore membrane smooth. 
11. Sp. insignis, Hass. 
** Spore membrane punctate. 
12. Sp. calospora, Cleve. 
B. Chlorophyll bands single. 
* Spore membrane smooth, 
13. Sp. quadrata, Petit. 
14. Sp. Weberi, Kutz. 
15. Sp. tenuissima, Hass. 
¥* Spore membrane punctate. 
None. 
