MARINE ALG^E OF BEAUFORT, N. C. 409 



Forty-eight species, mostly in fresh water or in damp places, some in salt water, 

 some in the tissues of other plants; throughout the world. 

 Chroococcus turgidus (Kuetzing) Naegeli. 



Protococcus turgidus, Kuetzing. 1845, torn, i, pi. 6, f. i. 



Chroococcus turgidus, Naegeli, 1849, p. 46. 



Chroococcus turgidus, Farlow, 1882, p. 27. 



Chroococcus turgidus, Wolle, 1887, p. 334. pi. 210, f. 40-41. 



Chroococcus turgidus, Forti, in De Toni, 1907, p. n. 



Chroococcus turgidus, Tilden, 1910, p. 5, pi. i, f. 3. 



P. B. -A. Nos. 751, 2202. 



Cells spherical, oblong-elliptical, or more or less angular from mutual pressure, single or associated 

 in families of two, four, rarely eight, 13 to 25, rarely 40 mic. in diameter; sheaths thick, usually lamellose, 

 hyaline, cell wall thin, cell contents pale blue-green, homogeneous, later becoming brownish and 

 granular. 



On moist rocks and occasionally in salt marshes throughout the world. 



Very abundant, with Microcoleus chthonoplastes and Plectonema battersiion ocean beach at Ocracoke, 

 N. C. (?); covering many square meters just beyond high-tide line, August, 1907, on shells in Pamlico 

 Sound; fairly abundant on rocks and shells and on Gelidium coerulescens, Fort Macon and Duncan 

 breakwater, Beaufort, N. C. (?), forming small masses not visible to the naked eye. 



The material from Core Sound and from Beaufort seemed to belong to this species but occurred so 

 scatteringly that it could not be obtained in sufficient quantity for a positive determination. 



Order 2. Hormogoneae (Thuret) Kirchner. 



Nostochineae, Farlow, 1882, p. 29. 



Plants multicellular, rarely unicellular (Spirulina), filamentous, attached to a sub- 

 stratum or free floating; filaments simple or branched, usually consisting of one or more 

 rows of cells within a sheath ; multiplication occurs by means of hormogonia or resting 

 gonidia. 



KEY TO FAMILIES. 



a. Filaments attenuated at apex, usually tapering to a hair; attached at base. .4. RIVULARIACE^ (p. 416). 



aa. Filaments never 'tapering to a hairlike apex b. 



b. Filaments simple or branched, if branched having several or many trichomes within 



each sheath, heterocysts lacking i. OSCILLATORIACE/E (p. 409). 



bb. Filaments simple, heterocysts present 2. NosTOCACE^E (p. 414). 



bbb. Filaments (or trichomes) regularly branched, having only one trichome within the 



sheath, heterocysts present 3. SCYTONEMACE/E (p. 415). 



Family 1. OSCILLATORIACEJE (Gray) Kirchner. 



Trichomes simple, composed of similar vegative cells, rarely unicellular, usually 

 surrounded by a sheath; filaments simple or rather sparsely branched, containing one or 

 more trichomes; filaments and trichomes rarely occurring scattered, -usually forming 

 scum, membranes, mats, etc.; propagation by hormogonia; no heterocysts. 



Usually blue-green, less often violet or brownish, rarely red. Cells usually short- 

 cylindrical or disk-shaped; less often barrel-shaped, in Spirulina long cylindrical and 

 spirally twisted. Apical cell rounded or wedge-shaped, sometimes calyptrate, some- 

 times tapering slightly. Filaments usually straight, often curved or spirally twisted at 

 the apices, in certain genera spirally twisted throughout the entire length. Often 

 several trichomes occur within a single more or less coarse sheath, forming a single fila- 

 ment. Sheaths sometimes delicate and inconspicuous, sometimes coarse, even exceeding 

 the diameter of the trichome; walls of sheaths sometimes very firm, sometimes gelat- 



