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Algal Flora of the Tropics . 
14. Ophiocytium cuspidaium (Bail.), Rabh. — ( a ) Borge, ’ 99 , p. 9 (Guiana!). 
15. Ophiocytiuvi gracilipes, A. Br. — (a) Lemmermann, ’ 05 , p. 631 (Oahu, 
small grotto between Honolulu and Pali); (b) Gutwinski, ’02 a, p. 577 ; (c) Lem- 
mermann, ’ 06 , p. 160 (same as a) ; (d) Bohlin, ’ 97 , p. 30 (Matto Grosso 1 ). 
1 6. Ophiocytiuvi majus , Nag. — (a) Turner, ’ 92 , p. 154 (Northern India!); 
(b) West and West, ’97 a, p. 236 (Pungo Andongo ; in stagnis prope Anbilla, 
Condo); (<r) Lagerheim, ’ 93 , p. 159 (also var. gordianum , Istv. ; with Ulricularia 
injlexa , Forsk.) ; (d) Borge, ’ 96 , p. 7 (Johnstone River, Queensland). 
17. Ophiocytium parvulum , A. Br. — [a) West and West, ’02 a, p. 161 (in 
muddy rice-field) ; ( b ) West and West, ’97 a, p. 236 (Pungo Andongo; in stagnis 
prope Anbilla, Condo); (c) West and West, ’02 b, p. 131 (stream, Victoria Park, 
Colombo); (d) Schmidle, ’ 95 , p. 296 (no locality); ( e ) Schmidle, ; 02 a, p. 64 
(Abo River); (p) Lagerheim, ’ 90 , p. 13 (en los pantanos en S. Rita); ( g ) Bohlin, 
’ 97 , p. 29 (Paraguay, Matto Grosso!). 
The most important form, as far as number of species and records go, 
is thus Ophiocytium. Conferva (especially if we follow Schmidle and 
exclude C. sandvicensis , A g.) is not very well represented, and a perusal of 
the records of this genus shows that, like Rhizocloniuin and Cladophora , it 
favours well-aerated water (rivers and waters at a high altitude). In 
Ceylon I have only met with occasional filaments of Conferva , although 
future more thorough investigation is sure to disclose a number of 
the unicellular forms ; certainly, however, none of them is abundant. One 
cannot help thinking of the peculiar type of assimilation as another 
explanation of the scarcity of Conferva (i. e. in addition to its apparent 
desire for well-aerated water). As in the case of Vancheria and Botrydimn , 
however, this point must remain open until we have far more precise data as 
to the kind of tropical habitats frequented by these forms. 
(iv) The Ulotrichales in the Tropics. 
It is not quite apparent from existing data whether the Ulotrichales 
are really rarer in the tropics than in temperate waters. I am tempted to 
such a conclusion by my observations in Ceylon, where they certainly, as 
far as the lowland waters are concerned, are relatively scarce. Messrs. 
W. and G. S. West, in their work on the freshwater Algae of Ceylon (West 
and West, ’02 B, p. 124), also comment on this fact ; they say : 4 Very few 
Algae were observed belonging to the families Confervaceae and Ulotri- 
chaceae ; this we are unable to account for, as many of the collections were 
from suitable localities for these plants.’ It again does not seem likely that 
Ceylon is exceptional, although possibly poorer in these forms than other 
parts of the tropics. As far as existing data go, there is nothing in the 
records of tropical Ulotrichales to point to their being bound to special 
conditions, and I think, therefore, that it will be sufficient to enumerate 
the species of this group so far recorded from tropical freshwaters. The 
