247 
Algal Flora of the Tropics. 
in the tropics, I will give a list of the blue-green (subaerial and freshwater) 
genera as yet known to occur in these parts of the world. The number 
in brackets after each genus refers to the approximate number of species 
recorded ; I should have liked to have given a full list of species and 
records, but space does not allow of that. Literature references are only 
given in the case of new genera. The genera are arranged according to 
Kirchner’s classification (in Engler and Prantl, Die natiirlichen Pflanzen- 
familien, i. Teil, Abt. i a, 1900, p. 45 et seq.) : — 
I. Chroococcaceae : — Chroococcus , Nageli (1 7); Synechococcus, Nageli (2); 
Gloeocapsa , Kiitz. (15) ; Placoma , Schousboe (1) ; Gloeothece , Nageli (5); Aphanocapsa , 
Nageli (4); Aphanothece , Nageli (9); Microcystis , Kutz. (6); Clathrocystis , Henfrey 
(2) ; Gomphosphaeria, Kutz. (1) ; Coelosphaerium , Nageli (4) ; Merismopedia, Meyen (6) ; 
Pilgeria , Schmidle (n. gen. in Schmidle, ’01 a, p. 53) ; Tetrapedia , Reinsch (10). 
II. Chamaesiphonaceae : — Xenococcus , Thuret (1) ; Dermocarpa, Crouan (1) ; 
Chamaesiphon, A. Braun et Grunow (incl. Sphaerogonium, Rostaf.) (8). 
III. Oscillatoriaceae : — ■ Oscillatoria , Vauch. (28); Arthrospira, Stitzenberger 
(1); Spirulina , Turpin (10); Phormidium , Kutz. (22); Proterendothrix , W. and 
G. S. West (n. gen. in West and West, ’97 a, p. 299) ; Lyngbya , C. A. Agardh (24) ; 
Hypheothrix , Kiitz. (10); Symploca , Kutz. (8); Porphyrosiphon , Kutz. (1); Hydroco - 
leum , Kiitz. (3); Inactis , Kiitz. (2); Schizothrix (Kiitz.), Gom. (16) ; Polychlamydum , 
W. and G. S. West (n. gen. in West and West, ’97 a, p. 271) ; Dasygloea, Thwaites 
(1) ; Microcoleus , Desmazieres (6). 
IV. Nostocaceae: — Nostoc, Vauch. (20) ; Nodularia, Mertens (2); Anabaena , 
Bory (incl. Sphaerozyga, A g.) (12) ; Cylindrospermum, Kiitz. (6); Aulosira , Kirchner 
(1); Microchaete , Thuret (1) ; Desmonema , Berkeley and Thwaites (1). 
V. Scytonemataceae : — Plectonema , Thuret (5) ; Scytonema , C. A. Agardh (40) ; 
Tolypothrix , Kiitz. (14). 
VI. Stigonemataceae : — Mastigocladus, Cohn (2) ; Chondrogloea , Schmidle 
(n. gen. in Schmidle, ’02 b, p. 247) (2) ; Hapalosiphon , Nageli (13) ; Fischerella , 
Gomont (1); Stigonema, C. A. Agardh (14); Camptylonema, Schmidle (n. gen. in 
Schmidle, ’00 a, p. 18 1); Capsosira, Kiitz. (1); Nostochopsis , Wood (1); 
derma , Schmidle (n. gen. in Schmidle, ’02 b, p. 246) (1). 
VII. Rivulariaceae : — Leptochaete , Borzi (1) ; Calothrix , C. A. Agardh (incl. 
Lophopodium , Kiitz.) (18); Dichothrix> Zanardini (6); Rivularia (Roth), C. A. 
Agardh (incl. Gloeotrichia, J. Ag.) (9). 
VIII. Camptotrichaceae : — Camptothrix , W. and G. S. West (n. gen. in West 
and West, ’97 a, p. 269). 
This list needs little further comment, since it shows the very large 
number of species and genera already recorded, and there is no doubt 
that their number will still be very considerably added to. Many of the 
species have been recorded from a large number of different localities, 
whilst in others the range at present appears to be restricted. Attention 
may also be particularly drawn to the great part played by Scytonema- 
