IQ THE FLORA OF NEBRASKA. 



Family.— CHROOCOCCACEAE. 



The characters of the order. 



SYNOPSIS. 



Chroococcus.— Cells associated in globose, amorphous families; cell-membrane thin, 



simple. 

 Gloeocapsa.— Cells in amorphous families with thick, many -layered sheaths. 

 Microcystis.— Cells very small, numerous, aggregated into globose bodies. 

 Merismopedia.— Cells very small associated in quadrate families of one layer. 



1. CUROOCOCCUS Naeg. Gatt. Einzell. Alg. 47. 1849. 



Cells globose or angular from mutual pressure, solitary or associated in glo- 

 bose, amorphous families; cell contents not chlorophyll-green; propaga- 

 tion by division alternately in three directions. 

 Etymology: Greek, xpog, color, and kokkoq, berry. 

 Chrooeocens cohaerens (Breb.) Naeg. 1. c. 



Pleurococcus cohaerens (Breb.) Menegh. Nostoch. Ital. 35. 



Cells oblong, in twos or fours with a distinct hyaline sheath; cell-membrane 



thin, cell-contents blue green, cells 4-6 fi in diam. 

 Stagnant water, Thedford. PI. I., Fig. 1. 



2. GLOEOCAPSA Kuetz. Phyc. Gen. 173. 1843. 



Cells usually spherical or somewhat oblong with vesiculiform sheath; 

 cell-membrane thick, often exceeding the cell-contents in diameter, color- 

 less or colored, usually in layers; cells undergoing division into two 

 daughter-cells, each with a distinct sheath, the whole being surrounded 

 by the sheath of the mother-cell, this process often repeated, the 

 original sheath remaining about the family thus formed. 



Etymology: Greek y?Mog, sticky, and m-tya, box. 

 Gloeocapsa arenaria (Hass.) Rabh. Fl. Eur. Alg. II, 39. 1865. 

 Haematococcus arenarius Hass. Freshw. Alg. 330. 1845. 



Masses mucilaginous, slightly olive colored; sheath thick, spherical, colorless, 

 somewhat lamellose; lamellae diffluent; cells aeruginous, 2-4 \i in diam. 



On flower pot in greenhouse, Lincoln. PI. I., Fig. 3. 



3. MICROCYSTIS Kuetz. Linn. VIII., 349. 1833. 



Cells very small, numerous, aggregated into globose bodies, surrounded by a 

 thin membrane; cell-masses usually single or rarely several, surrounded 

 by one sheath. 

 Etymology: Greek {iinpog, small, and nvgrig, bladder. 

 Microcystis protogenita (Bias.) Rabh. Fl. Eur. Alg. II, 52. 1865. 

 Micraloa protogenita Bias. Alg. Micro. 47. 1833. 



Families ordinarily subspherical, 15-75 // in diam.; single cells 4-6J£ fi in 

 diam.; color primarily aeruginous but changing to light yellow or orange. 

 Around wells, in water tanks, etc. PI. I., Fig. 2. 



4. MERISMOPEDIA Meyen Wiegm. A.rchiv. 1839, page 67. 



Cells globose or at the time of division oblong; 4, 8, 12 to an indefinite num- 

 ber associated in families, forming a plane, quadrate stratum. 

 Etymology: Greek fiepia/iog, division, and nediov, plain. 

 Merismopedia glanca (Ehrb.) Naeg. Gatt. Einzell. Alg. 55. 1849. 

 Gonium glaucum Ehrb. Infus. 56. 1836. 



