THE ALGAE OF BERMUDA. 25 



NOSTOC Vaucher. 



*N. COMMUNE Vauchel- ex Bornet & Flahault, 1888, p. 203; P. B.-A., 

 No. 1901; N. dniflonum Bornet & Thuret, 18SO, p. 102, PI. XXVIII, 

 fig. 13. Common everywhere, especially on sandy soil; thin brittle 

 skins in dry weather, expanded thickish soft masses in wet weather. 

 No spores seen. Native name, "Devil's Tobacco." 



FAMILY SCYTONEMACEAE Kiitzing. 

 MICROCHAETE Thuret. 



M. VITIENSIS Askenasy ex Bornet & Flahault, 1887, p. 85. Scat- 

 tered filaments on Wrangclia penicillata, Harris Bay, Jan., Hervey. 



SCYTONEMA Agardh. 



1. Sheaths not lamellate. 2. 



1. Sheaths lamellate. 3. 



2. Trichomes 5-7 /* diam. 1. S. varium. 



2. Trichomes 6-14 /j. diam. 2. S. ocellatum. 



3. Branches usually geminate, free and divergent. 4. 



3. Branches frequently solitary, adherent at base. 5. S. crustaceum. 



4. Filaments 15-21 /* diam.; sheath thin at apex. 3. S. figuratum. 



4. Filaments 18-36 /j. diam.; sheath thick throughout. 4. S. myochrous. 



*1 . S. VARIUM Kiitzing ex Bornet & Flahault, 1887, p. 97; Kiitzing, 

 1850-52, p. 6, PI. XXIII, fig. II. High up on walls of a cave at Wal- 

 singham; shore of pool near Walsingham, April, Collins. 



*2. S. OCELLATUM Lyngbye ex Bornet & Flahault, 1887, p. 95; 

 P. B.-A., No. 711, on dunes, Paget, Farlow. 



*3. S. FIGURATUM Agardh ex Bornet & Flahault, 1887, p. 101; 

 S. thermalc Kiitzing, 1850-52, p. 5, PI. XVIII, fig. III. High up on 

 wall of cave near Walsingham, April, Collins. 



Bornet, 1889a, p. 155, shows that Conferva mirabiJis Dillwyn, 1807, 

 PI. XCVI, is identical with Scytoncma figuratum of Agardh, and of 

 earlier date, and therefore changes the name to S. mirabile (Dillw.) 

 Bornet. But as the starting point for nomenclature of the hetero- 

 cysted Nostochaceae is definitely fixed at the Bornet & Flahault 

 monograph, it appears as if the later name by Bornet cannot be sub- 

 stituted. 



