Myxophyceae 297 



sheaths at first thin, becoming thick, finally diffluent into a gelatinous mu- 

 cus; reproduction by cell division in all directions. 



543. Porphyridium cruentum (Agardh) Naegeli. Gatt. Einzell. Alg. 139. pi. 



4. 1849. De Toni. Syll. Algar. 5: 697. 1907. 



Buchanan. Notes on the Algae of Iowa. Proc. Iowa Acad. Sci. 14: 9. 

 1908. 



Plate XX. fig. 23. 



Plant mass often widely expanded, membranaceous, mucous, of a dark 

 red color, sometimes becoming greenish; cells 6.5-9 mic. in diameter, spheri- 

 cal or angular by mutual pressure; cell contents reddish purple. 



Iowa. (Buchanan). 



Family II. CRYPTOGLENACEAE 



Plants unicellular, blue-green, floating free in water; vegetative cells el- 

 liptical, oval or almost wedge-shaped, bearing two cilia of equal length, not 

 motile; cell walls thin, close, colorless; chromatophores disc-shaped, adher- 

 ing to the wall, enclosing somewhat spherical pyrenoids. 



Genus CRYPTOGLENA Ehrenberg. 

 Abhandl. Akad. Wiss. zu Berlin. 150. 1832. 



Cells marked by a conspicuous red pigment spot; cell wall often sepa- 

 rated from the protoplasm, forming a sac. 



544. Cryptoglena americana Davis. Notes on the Life History of a Blue- 



green Motile Cell. Bot. Gaz. 19: pi. 11. 1894. De Toni. Syll. Al- 

 gar. S: 700. 1907. 

 Collins. Preliminary Lists of New England Plants. — V. Marine Algae. 

 Rhodora. 2: 41. 1900. 



Plate XX. fig. 24, 25. 



Motile cells S-6 mic. in diameter, 8-10 mic. in length, broadly elliptical, 

 hyaline on one end, slightly truncate, with a depression from which arises 

 a pair of cilia of unequal length, the longer one about as long as the cell 

 is wide; cell contents blue-green, with six to ten disc-shaped chromato- 

 phores arranged around the periphery, and with one or two bright red 

 pigment spots placed on the periphery, near the middle of the cell; non 

 motile cells 6-7 mic. in diameter, 7-9 mic. in length, arranged in groups of 

 twos and fours in a closely packed Polycystis-like colony, almost imiformly 

 colored blue-green, with six to ten disc-shaped chromatophores and one or 

 two brownish red pigment spots near the middle of the cell at the per- 

 iphery; nucleus near the middle of the cell. 



Massachusetts. On stems of grass and larger algae. Salt marshes of thf 

 Charles River, Cambridge. Autumn. (Davis). 



