28 COLLINS AND HERVEY. 



DiCHOTHRix Zanardini. 



1. On rocks; filaments 15-20 n in branches of last order. 1. D. Baueriana. 

 1. Epiphytic; filaments 20-30 /x in branches of last order. 2. D. fucicola. 



*1. D. Baueriana Bornet & Flahault, 1886, p. 376. On rocks 

 between tides, North Shore, Oct., Nov., Hervey; Hamilton Harbor, 

 Nov., Collins. Known heretofore only as a fresh water species, but 

 the Bermuda plant is distinctly marine, though agreeing in characters 

 with European and American specimens from fresh water stations. 



2. D. FUCICOLA Bornet & Flahault, 1886, p. 379; Schizosiphon 

 fucicola Kiitzing, 1850-52, p. 18, PI. LV, fig. II. On various algae 

 forming a mat at the bottom of a pool. Gibbet Island, Hervey. 



PoLYTHRix Zanardini. 



P. coRYMBOSA Grunow ex Bornet & Flahault, 1886, p. 380; P. B.-A., 

 No. 1903; Microcoleus corymhosus Harvey, 1858, p. 109, PI. XLVIII. 

 B. Common on rocks between tides in quiet water all around the 

 islands. 



RlVULARIA Roth. 



R. POLYOTis Bornet & Flahault, 1886a, p. 360; P. B.-A., No. 1904; 

 R. hospita Bornet & Thuret, 1880, p. 168, PI. XLI. Rocks near high 

 water. South Shore, Feb., April, Collins; grotto, Tucker's Town, 

 Dec, Hervey. 



Brachytrichia Zanardini. 



B. MACULANS Gomont, 1901, p. 127, PI. V, figs. 5-7; P. B.-A., 

 No. 2159. Forming a thin film on roots etc. of mangroves between 

 tides, in company with Dichothrix and Calothrix species, Fairyland, 

 Dec, Collins. 



Originally described from material collected in Siam, this species 

 now makes its second appearance half way round the globe. 



Family CRYPTOGLENACEAE. 

 Cryptoglena Ehrenberg. 



C. AMERICANA B. M. Davis, 1894, p. 101, PI. XI; P. B.-A., No. 1851. 

 Among Cladophora expansa and other algae, in a brackish pool be- 

 tween Harrington Sound and the North Shore, April, Collins. 



