MARINE ALG 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) Negeli. 
Protococcus turgidus, Kuetzing, 1845, tom. 1, pl. 6, f. 1. 
Chroococcus turgidus, Nwgeli, 1849, p. 46. 
Chroococcus turgidus, Farlow, 1882, p. 27. 
Chroococcus turgidus, Wolle, 1887, p. 334, Dl. 210, f. 40-41. 
Chroococcus turgidus, Forti, in De Toni, 1907, p. rr. 
Chroococcus turgidus, Tilden, 1910, p. 5, pl. 1, 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 battersii on 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 cerulescens, 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. Hormogonee (Thuret) Kirchner. 
Nostochinee, 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). 
aaaFilaments nevertapering toa bairlike apex: oo... 0. csusseasarncwenmeu wnat cane dea OeMIR ce b. 
b. Filaments simple or branched, if branched having several or many trichomes within 
each sheath, ;heterocysts lackixigy:c! eet Mocs cet! pele eden des 1. OSCILLATORIACEA (p. 409). 
bb. Filaments simple, heterocysts present .............00-e geese eee e eee eee 2. NOSTOCACE& (p. 414). 
bbb. Filaments (or trichomes) regularly branched, having only one trichome within the 
SHEATH METELOCYStS PLESEME 5.625. wcisiaieis eign aioe oicha sien < «chee nice cae 3. SCYTONEMACE4! (p. 415). 
Family 1. OSCILLATORIACEZ (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- 
