This genus should be compared with Anacystis {Aphanothece, 

 Gloeothece), a genus with elongate cells inclosed in hyaline muci- 

 lage and with cells usually aggregated in large numbers to form 

 colonies. 



Sijnechococcus aeruginosus Naegeli 1849, p. 56 

 PL 102, Figs. 6-8 

 Cells oblong to cyhndric, 2-3 times their diameter in length, 

 poles broadly rounded; soHtary or in pairs; 7-15)u, in diameter, 

 14-25/x long. 



Rare in tychoplankton and in films of algae on sandy beaches. 

 Mich., Wis. 



GLOEOTHECE Naegeli 1849, p. 57 

 Ovate or cylindrical cells inclosed by definite, often lamellated 

 sheaths and embedded in copious mucilage to form amorphous 

 gelatinous masses, either free-floating or attached, often occurring 

 with Aphanothece spp. See notes under that genus, p. 465, concern- 

 ing the combining of Gloeothece and Aphanothece under Anacystis 

 Meneghini. 



Key to the Species 



1. Colonial mucilage and cell sheaths ■ 



golden- or yellow-brown G. fusco-lutea 



1. Colonial mucilage colorless 2 



2. Cells 1.2-2.5At in diameter, up to 18m long, cylindrical with 



rounded apices, each cell faintly sheathed G. linearis 



2. Cells 4-6/u. in diameter, up to 15/ix long; individual cell sheaths 



conspicuous, sometimes several cells inclosed by one sheath G. rupestris 



Gloeothece fusco-lutea Naegeli 1849, p. 58 

 Cells oblong-cylindric, inclosed in amorphous mucilage with in- 

 dividual sheaths thick and golden-brown in color; cell contents 

 blue-green; cells 4-5.5^ in diameter, 7.4-9/1. long. 

 Tychoplankter. Wis. 



Gloeothece linearis Naegeli 1849, p. 58 

 [Anacystis Peniocystis (Kuetz.) Drouet & Daily in Daily 1942, p. 651] 



PI. 102, Fig. 9 

 Cells cylindrical, vermifonn, or bacilliform, about 10 times their 

 diameter in length, loosely scattered in small, free-floating, irregu- 

 larly saccate or elongate-bulbous colonies, with long axes of the 

 cells approximately parallel, ends of the cells rounded; colonial 

 mucilage hyaline or yellowish and faintly lamellated, each cell 



[ 461 ] 



