Myxophyceae 41 



•Pennsylvania. Forming a dense scum on a stagnant brick pond, near 

 Philadelphia. July. "The scum was of the color of 'pea-soup' and so thick 

 was it, that I think a quart of the plants might have been readily gathered." 

 (Wood). 



Genus COELOSPHAERIOPSIS Lemmermann. 

 Abh. Nat. Bremen. 16: 352. 1899. 



Colonies spherical, gelatinous, hollow; families clustered; cells spherical 

 or elongate, arranged in a single peripheral layer; reproduction by cell 

 division. 



55. Coelosphaeriopsis halophila Lemmermann. Planktonalgen. Ergeb. 



einer Reise n. d. Pacific. Abh. Nat. Bremen. 16: 353. pi. 2. f. 25, 26, 



1899; Algenfl. Sandwich.-Inseln. Bot. Jahrb. 34: 616. pi. 7. f. 19-21. 

 1905. De Toni. Syll. Algar. 5: 103. 1907. 



Plate II. fig. 30. 



Colonies 30-500 mic. in diameter, spherical, gelatinous; cells 6 mic. in 

 diameter, 6-9 mic. in length, spherical or elongate. 



Hawaii. In salt lagoon. Island of Laysan. (Schauinsland). 



Genus TETRAPEDIUM Reinsch. 

 Algenfl. von Franken. 37. 1867. 



Cells solitary or occurring in families of from 2-16 each, compressed, 

 quadrangular or triangular, equilateral, becoming subdivided into quadrate 

 or wedge-shaped segments or rounded lobes, either by deep vertical or 

 oblique incisions or by wide angular or rounded sinuses; cell contents blue- 

 green; reproduction by cell division. (Single cells break apart by the in- 

 cisions into four daughter cells each, the daughter cells after division 

 forming separate individuals. The direction of the incisions is either per- 

 pendicular to the lateral margin or bisects the angles.) 



96. Tetrapedium trigonum. W. and G. S. West. On some Freshwater 

 Algae from the West Indies. Journ. Linn. Soc. Bot. 30: 277. pi. 16. 

 f. 8. 1895. De Toni. Syll. Algar. 5: 113. 1907. 



Plate II. fig. 31. 



Cells 3.6x7.2 mic, triangular, with concave sides and somewhat rotund 

 angles, elliotical in side view; cell contents homogeneous, pale blue-green. 



West Indies. On damp wall of dam. Sharp's River, St. Vincent. May 

 1892. (Elliott). 



Genus MERISMOPEDIUM Meyen 

 in Wiegmann Archiv. 2: 67. 1839. 



Colonies flat, rectangular, free-floating; tegument somewhat thick, con- 

 fluent; cells spherical, before division oblong, arranged in a rectilinear 

 series in a single layer; cell contents usually without gas vacuoles, blue- 



