622 OSCILLATOKIACEAE. 



Abundant in 4-5 m. water, forming pulvinate masses among Thalassia, Penicillus 

 etc., Cockburn Harbor, South Caicos Island, December 16, 1907, M A Howe 5593 

 (type). 



Nearest allied to P. Retzii, but differing by the firmer and more persistent 

 sheaths, the uniformly cylindrical trichomes and the generally longer cells, as well 

 as by the distinctly marine habitat. There is more or less lime scattred through the 

 mass, but incidentally ; it does not form a stony mass as in the encrusting species. 



4. LYNGBYA Ag. ex Gomont, Monogr. 138. 1893. 



Filaments attached at the middle, both ends free. 1. L. graciUs. 



Filaments attached at one end or without definite point of at- 

 tachment. 



Filaments spirally wound about some other filamentous alga. 7. L. epipJu/tica. 

 Filaments not epiphytic and spiral. 



Trichomes 4 M in diameter or less, seldom over 3 W . 6. L. Lagerheimii. 



Trichomes over 5 in diameter. 



Trichomes usually 20-40 u. in diameter: length of cells 

 1/6-1/15 of the diameter ; dissepiments not gran- 

 ulate. 3. L. majuscula. 

 Trichomes usually 16 in diameter or less: length of 

 cells 1/31/8 of the diameter ; dissepiments usu- 

 ally granulate. 

 Trichomes usually 9-16 # in diameter; apex not 



attenuate nor capitate ; stratum usually yellow. 4. L. conferroides. 

 Trichomes usually more or less attenuate and capi- 

 tate. 



Sheath becoming yellowish or brownish with 

 age ; stratum mostly aeruginous or rusty ; tri- 

 chomes usually 10-1 6 w . 2. L. aestuarii,. 

 Sheath always hyaline ; stratum dull or yellow 



green; trichomes 7-10 in diameter. 5. L.semiplena. 



1. Lyngbya gracilis Bab. ex Gomont, Monogr. 145. pi. 2. f. 20. 1893. 



Among other algae, Exuma Chain : Europe ; North America. Type from Italy. 



2. Lyngbya aestuarii (Mert.) Liebmann ex Gomont, Moiiogr. 147. pi. 3. f. 1-2. 



1893. 



Exuma Chain : common on all shores. Type from Denmark. 



2a. Lyngbya aestuarii forma limicola Gomont, Monogr. 149. 1893. 



Exuma Chain, with the typical form ; of same distribution. Type station un- 

 known. 



3. Lyngbya majuscula Harv. ex Gomont, Monogr. 151. pi. 3. f. 3-4. 1893. 



New Providence, Berry Islands, Exuma Chain, Watling's Island, Atwood Cay, 

 Mariguana, Caicos Islands, Great Ragged Island : everywhere in tropical and warm 

 temperate waters. Type from England. 



4. Lyngbya confervoid.es Ag. ex Gomont, Monogr. 156. pi. 3. f. 5-6. 1893. 



New Providence, .Toulter's Cay, Bimini, Berry Islands, Exuma Chain, Watling's 

 Island, Cat Island, Mariguana, Caicos Islands, Great Ragged Island : generally 

 distributed in tropical and warm temperate waters. Type from Spain. 



5. Lyngbya semiplena J. Ag. ex Gomont, Monogr. 158. pi. 3. f. 7-11. 1893. 



New Providence, Berry Islands, Great Bahama, Exuma Chain, Watling's Island, 

 Atwood Cay. Mariguana, Great Ragged Island: generally distributed. Type from 

 the Mediterranean. 



6. Lyngbya Lagerheimii Gomont, Monogr. 167. pi. 4. f. 6-7. 1893. 



Caicos Islands : Europe ; North and South America. Type from Brazil. 



7. Lyngbya epiphytica Hieronymus; Kirchner in Engl. & Prantl, Nat. Pflan- 



zenfam. l la : 67. 1898. 



Winding about the filaments of Lyngbya sp. ; Watling's Island, Atwood Cay : 

 Europe ; North America. Type from Germany. 



