20 COLLINS AND HERVEY. 



5. O. CORALLINAE Gomont, 1893, p. 238, PI. VI, fig. 21. On 

 Codium tomentosum, Cooper's Island, April, Collins. 



*6. O. TENUIS Ag. var. TERGESTINA Rabenhorst ex Gomont, 1893, 

 p. 241. Among other algae in a ditch in meadow by Shelly Bay, Aug., 

 Collins. 



*7. 0. AMPHIBIA Gomont, 1893, p. 241, PL VII, figs. 4-5; P. B.-A., 

 No. 1852. In brackish pool among other algae, April, Aug., Collins. 



*8. O. AMOENA Gomont, 1893, p. 245, PI. VII, fig. 9. Forming a 

 thin coating on rock at Inlet, Aug., Collins. 



*9. O. LAETEVIRENS Crouan ex Gomont, 1893, p. 246, PI. VII, 

 fig. 11. Among other algae, Tucker's Town, May, Collins. 



*10. O. FORMOSA Bory ex Gomont, 1893, p. 250, PI. VII, fig. 16. 

 In a puddle of rain water in road, April, Collins. 



11. O. LONGEARTICULATA Hansgirg ex Forti, 1907, p. 176. On 

 Codium, near Causeway, April, Hervey. We have not seen an au- 

 thentic specimen of this species, but our plant agrees with the original 

 description, w r ith no description in Gomont, and with none but this 

 in Forti. 



TRICHODESMIUM Ehrenberg. 



T. THIEBAUTII Gomont, 1893, p. 217, PI. VI, figs. 2-4; Wille, 1904, 

 p. 57, PI. I, figs. 17-22. Hamilton Harbor, Wille, 1. c. 6 



PHORMIDIUM Kiitzing. 



1. Trichomes strongly moniliform. 1. P. fragile. 



1. Trichomes not moniliform. 2. 



2. Stratum purple or pink. 2. P. luridum. 



2. Stratum greenish or blackish. 3. 



3. Trichomes 3 M diam. or less. 3. P. valderianum. 



3. Trichomes 4-12 fj. diam. 4. P. Retzii. 



1. P. FRAGILE Gomont, 1893, p. 183, PI. IV, figs. 13-15. Among 

 other algae in an incrustation in rock between tide marks, April, 

 Collins. 



*2. P. LURIDUM Gomont, 1893, p. 185, PL IV, figs. 17-18; P. B.-A., 



6 Catagnymene pelagica Lemmermann var. major Wille, 1904, p. 51, pi. I, 

 fig. 7, is reported by Tilden, 1910, p. 159, as occurring at Bermuda, but we 

 are unable to obtain any confirmatory evidence. Wille, 1. c., reports it from 

 open sea, at several points. Dermocarpa Leibleinii (Reinsch) Bornet var. 

 pelagica Wille, also appears in Tilden, 1910, p. 55, as from Bermuda, on 

 authority of Wille, 1904, p. 50; but Wille's record is 39 4' X., Long. 57 8' W., 

 " ungefahr in der Mitte zwischen den Bermuda-Inseln und New Foundland." 



