620 OSCILLATOBIAOEAE. 



crust of a brown color ; the cells are somewhat larger than in the present species, 

 and brownish or yellowish. E. violacea approaches the genus Placoma in the ten- 

 dency of the cells to arrange in radiate filameuts, but the tendency is less marked 

 than in Placoma, and the frond is closely adherent to the substratum, not buUate 

 and hollow as in Placoma. 



5. GLOEOTHEOE Nag. Gatt. 57. 1849. 



1. Gloeothece rupestris (Lyngb.) Bornet; Wittr. & Nordst. Alg. Exsice. 399. 

 1880. 

 Palmella rupestris Lyngb. Tent. 207. pi. 69. f. D. 1819. 



On rocks, nearly pure, Caicos Islands : — common everywhere in small quantity 

 among other algae, especially in shallow pools, both alongshore and inland ; of gen- 

 eral distribution. Type from Denmark. 



Very variable ; teguments often diffluent, giving the appearance of Aphanothece. 



6. ONCOBYBSA Ag. Elora 10: 629. 1827. 



1. Oncobyrsa marina (Grun.) Eab. Elor. Eur. Alg. 2: 68. 1865. 



Eydrococcus marinus Grun. Verh. Zool.-Bot. Ges. Wien. 11 : 420. 1861. 



On Chondria, Mariguana ; — Europe ; Africa ; Bermuda. Type from the Medi- 

 terranean. 



Family 2. CHAMAESIPHONACEAE. 



1. HYEIJiA Born. & Elah. Jour, de Bot. 2: 162. 1888. 



1. Hyella caespitosa Born. & Flab. loe. cit. 



In dead shel's, common : — generally distributed. Type from France. 



2. DEE-MOCABrPA Crouau, Ann. Sei. Nat. Bot. IV. 9: 70. 1858. 



1. Dermocarpa prasina (Eeinseb) Bornet & Thuretj Notes Alg. 75. pi. S6. f. 

 6-9. 1880. 



Sphaenosiphon prasinus Eeinsch, C'ontrib. 17. pi. 26. f. 1. 1875. 



On Catcnella Opuntia pinnata. Berry Islands ; probably to be found wherever 

 the host occurs : — Europe. Type from Europe. 



The common species of the New England coast, which has passed under this 

 name, has much larger cells, and was segregated by Borgeseu as D. Farlowii. 



3. XENOCOOCUS Thuret, Ann. Sci. Bot. VI. 1: 373. 1875. 



1. Xenococcus Schousboei Thuret in Born. & Tbur. Notes Alg. 76. pi. S6. f. 1-S. 

 1880. 



Attached to wall of Lyngbya sp., Atwood Cay ; — of general distribution. Type 

 from northern Africa. 



Family 3. OSCILLATORIACEAE. 



1. OSCILLATORIA Vaucber, ex Gomont, Monogr. 218. 1893. 



Trichomes not torulose, 4— 10/i in diameter. 4. O. tenuis. 

 Trichomes distinctly torulose. 



Stratum and trichomes red or red-brown. 2. 0. miniata. 

 Stratum and trichomes aeruginous or chalybeous. 



Trichomes 10-20u in diameter, apex straight. 1. O.sanota. 



Trichomes 6-10 « in diameter, apex usually curved. 3. O. Oorallinae. 



1. Oscillatoria s&mcta Ktitz. ex Gomont, Monogr. 22-9. pi. 6. f. 12. 18S3 



Atwood Cay : — generally distributed, normally in fresh water. Type from Italy. 



2. Oscillatoria miniata Hauck ex Gomont, Monogr. 236. 1893. 



Floating, with Trichodesmiiim Thieiantii, in Gulf Stream between Gun Cay and 

 Florida : — Bermuda ; Guadeloupe ; and Adriatic Sea. Type from Adriatic Sea. 



