212 
MESSRS. W. WEST AND G. S. WEST ON 
EXPLANATION OF THE PLATES. 
f 
a, à^ = cellula vel semicellula a fronte visa. 
Cd : : 
` Gd i, pitas e a vertice visa. 
c = i SG "m a latere visa. e 
d = semicellula a basi visa. 
PLATE 17. 
Figs. 1, 2. Gzdogonium suboctangulare,sp.n. x 220. 
2-5. pe spirale, Hirn, var. acutum, var. n. X 520. 
6, 7. Sg elegans, sp. n. x 520. 
8,9. Bulbochete spirogranulata, sp. n. x 520. 
10. 2 minuta, sp. n. x 520. 
ll. Herposteiron crassisetum sp. n. X 520. 
13, 13. Cladophora incurvata, sp. n. 12, x 3; 13, x 60. 
14, 15. Desmatractum plicatum, gen. et sp. n. 14, x 520; 15, x 830. 
16, 17. Scenedesmus quadricauda, Bréb., var. opoliensis, nob. x 520. 
18. Rhaphidium polymorphum, Fresen., var. Turnerii, nob. x 520. 
PLATE 18. 
Figs. 1, 2. Cylindrocystis pyramidata, sp. n. x 520. 
3, 4. Penium heterotaphridium, sp. n. x 520. 4, zygospore. 
5. » lanceolatum, W. B. Turn., var. suócylindricum, var. n. x 520. 
6. »  Spiros'riolatiforme, sp. n. x 520. 
"P » minutum, Cleve, var. elongatum, nob. x 520. 
8, 9. »  spinospermum, Josh., forma minor. x 520. 9, zygospore. 
10. »  variolatum, West & G. S. West, forma. x 520. . 
ll. Closterium subcompactum, sp. n. X 520. 
12. Gi pleurodermatum, sp. n. x 520. 
13. i striolatum, Ehrenb., var. robustum, var. n. x 520. 
14-16. e subporrectum, sp. n. X 520, 
A7, 18. 5 exiguum, sp. n. X 520. 
19. » validum, sp. ii. x 520. ` 
20. si Delpontii, Wolle, var. elongatum, var. n. x 520. 
21. » Kiitzingii, Bréb., var. vittatum, Nordst. Forma duplo-minor. x 520. 
22, 28 » gracile, Bréb., var. tenue, nob. x 520. 
24-26. 2 anastomosum, sp. n. X 520. 
27. Pleurotenium Ehrenberghii, De Bary, var. Borgei, var. n. x 520. 
28. a 4 " var. undulatum, Scliaarschm. x 520. 
29-32. » elatum, Borge, var. conjunctum, nob. ` Forma duplo-major. 29, 30, x 220; 
: 01,3925, «DD. = "nw 
33, 31. d Kayei, Rabenh. xX 520. ` 
