3S THE FLORA OF NEBRASKA. 



4. CLOSTERIIJIH Nitzsch. Beitr. Z. Infusorienk. 1817. 



Cells falcate or crescent shaped, rarely almost straight, fusiform or cylindri- 

 cal, entire, apex acuminate, not constricted in the middle; cell-contents 

 arranged in long parietal laminae; at the apex usually a colorless or 

 straw-colored vesicle containing granules which are in constant motion; 

 cell membrane thin, hyaline, in some cases colored and striate. 



Etymology: Greek k?umjt>ip, thread. 

 Closterinni acerosnm (Schrank) Ehrb. Inf. 92. 1836. 

 Vibrio acerosus Schrank Faun. Boic. III., 2, 47. 1803. 



Linear-fusiform, very slightly curved and gradually attenuate to the ends, 

 20-50 fi or even 65 /i in diam., 10-18 times as long; apex obtuse and straight; 

 membrane smooth or very delicately striate; pyrenoids 6-11 in a central 

 row in each half -cell, vacuole small, containing 12-20 vibrating corpuscles. 



Lincoln, Minden, South Bend. PI. V., Fig. 1. 

 Closterinni laneeolatum Kuetz. Phyc. Germ. 9. 1845. 



Closterium acerosum laneeolatum Klebs Desm. Preuss. 7. 1879. 



Fusiform or semilanceolate, slightly curved; upper margin convex, lower 

 nearly straight, ends tapering; apex conical, acute or subacute; membrane 

 slightly striate, hyaline, rarely dilute brown; pyrenoids in a simple cen- 

 tral series in each half-cell; diameter 50-55 /*, 6-9 times as long. 



Lincoln, Minden, South Bend, common. 

 Closterium striolatum Ehrb. Abh. 68. 1833. 



Cells slightly beut, 8-16 times longer than broad; ends reduced to about one- 

 fourth the largest diameter, apex obtusely rounded; membrane distinctly 

 striate, in older forms reddish-brown; striae 5-10 in number; pyrenoids 

 5-7 in each half-cell, large; cells in diameter 30-48 fi, in length 330-370//; 

 zygospore obicular, smooth. PI. V., Figs. 3 and 7. 

 Closterinni dianae Ehrb. Inf. 92. 1836. 



Narrowly fusiform, semilunate, 18-25 fi broad, 350 fi long, ends attenuate; apex 

 subacute; membrane hyaline, rarely dilute brown; striae very delicate; 

 pyrenoids 6-7 in an axial series in each half -cell; chlorophyll bands nu- 

 merous, often twisted; vacuole indistinct; zygospore globose, 36 ft in diam. 



Minden. PI. VI., Fig. 9. 

 Closterium acuminatum Kuetz. Phyc. Germ. 130. 1845. 



Slender, semi-lunate, 25-28 n broad, strongly attenuate at both ends, apex 

 acuminate; membrane hyaline, smooth or very slightly striate; pyrenoids 

 7-9 in an axial series in each half -cell, vacuole distinct, containing nu- 

 merous corpuscles. 



South Bend. PI. IV., Fig. 21. 

 Closterium parvulum Naeg. Einzell. Alg. 106. 1849. 



Small, semicircular, not swollen in the middle, narrowly lanceolate, 7-16 // 

 broad, 6-8 times as long, apex acute; membrane smooth or slightly stri- 

 ate, yellowish fuscous; pyrenoids 2-6 in an axial series in each half -cell, 

 vacuole indefinite. 



Creeks, Lincoln. PI. V., Fig. 8, a and b. 

 Closterium jenneri Ralfs Brit. Desm. 167. 1848. 



Cells cylindrical fusiform, crescent-shaped, attenuate, 6-8 times longer than 

 broad, apex obtusely rounded; pyrenoids 5-7 in a single axial series; 

 vacuoles large, containing many corpuscles; cells 12-14x65-87 /i. 



Lincoln. PI. VI, Figs. 10 and 10 a. 



