ALGE FROM THE WEST INDIES. 279 
60. Navicuna BoreaLIs, Kuetz. [Pinnularia borealis, Ehrenb., 
W. Sm. Brit. Diat. ii. p. 94; Rabh. Fl. Europ. Alg. i. p. 216.] 
Hab. With the preceding species. 
61. N. mesorerta, Ehrenb. [Pinnularia mesolepta, W. Sm. 
Brit. Diat. i. p. 58, t. 19. f. 182.] 
Hab. On bed of stream in crater of Grande Soufriére, Dominica. 
No. 881. 
62. Frusrutia rtomBorpEs, De Toni. (Sylloge Algar. vol. ii. 
p. 227.) [Navicula rhomboides, Hhrenb., W. Sm. Brit. Diat. i. 
p. 46, t. 16. £. 129.) 
Hab. In stream, crater of Grande Soufri¢re. No. 908. 
Var. saxontca, De Toni. (L.c.) [Frustulia saxonica, Rabh. 
Navicula crassinervia, Bréb. in W. Sm. Brit. Diat. i. p. 47, 
t. 31. f. 271.) 
Hab. In streams (cold, warm, and hot), crater of Grande 
Soufriére, Dominica. Nos. 883 and 908.—Also amongst mosses 
on trees, summit of Trois Pitons (4500 ft.), Dominica. Nos. 
903 and 904. 
63. GoMPHONEMA TENELLUM, Kuetz. (W. Sm. Brit. Diat. i. 
p- 80, t. 29. £. 243.) 
Hab. On damp wall of dam, Sbarp’s River, St. Vincent. 
No. 477. 
EXPLANATION OF THE PLATES. 
Puare XIII. 
Figs. 1-4. Zygnema (§ Zygogonium) pachydermum, n. sp. Conjugated spe- 
cimens, 520/1. 
5-8. Ditto. Four zygospores, 520/1. 
9,10. Ditto. ‘Two specimens, with azygospores, 520/1. 
11-15. Ditto, sterile filaments; fig. 11, 520/1; figs. 12-15, filaments, 
showing short branches, 120/1. 
Fig. 16. Ditto, showing conjugation between three filaments, 120/1. 
Fig. 17. Cosmarium obliquum, Nordst., f. minor, Nordst., 520/1. 
Puate XIV. 
Figs. 1-6, Zygnema pachydermum, Nn. sp., Var. confervoides, 0. var. Figs. 1 & 2, 
filaments without cell-contents; fig. 3, filament with contents 
delineated ; fig. 4, attempt at conjugation ? ; fig. 5, cells showing 
longitudinal division. Figs. 1-5, 520/1; fig. 6, 830/1. 
7-11. Microchete tenuissima, n. sp. 520/l. 
12-15. Scytonema javanicum, Bornet. 520/1. 
