THE FLOB \ OF M.l'.i; \SB \. 



Mongeotia gennflexa (Dillw.) Ag. l. o. 



Conf rva genuflexa Dillw. Brit. Conf. t. 6. L809. 



Pleurocarpus mirabilis A. Bb. of Wolle'a Fresh Water Algae >■!' U. s. 



Filaments in large masses, yellowish green, mucous; 25 ';" • in diam; cells 2 ."> 

 times as long as tho diameter; reproduction by the uni >n of 2 ad 

 cells of a filament, iu one or two cases scalariform eopulation ha 

 been observed; zygospores globose or oval, 30-35 » in diam. Two -t . -r-i 1 « - 

 filaments often bend towards each other. 

 Lincoln, Cedar Bluffs. PI. VIII.. Pigs. 1 and la. 



Sub-fam.— Zyi»'>H'iii«ae.^Chloroplasts either in one or many straight or 

 coiled parietal bands with irregularly denticulate margins, or central and 

 star shaped; membrane broad, often diffluent; reproduction by the union 

 of the protoplasm of 2 cells either of the same or of different filaments; 

 zygospore formed in one of the cells or in the connection between the 

 cells. 



2. ZYCJXEMA Ag. Syst.77. 1824. 



Includes Zygogonium Kuetz. Phyc. Gener. 280. 1843. 



Chloroplasts "J, axillary, near tho central nucleus; pluriradiate enclosing a 



single pyrenoid. 

 Etymology: Greek £vyov, yoke, and vtyia, thread. 



Zygiicina cruciatum (Vauch.) Ag. 1. c. 



Conjugate/, cruciata Vauch. Hist. Conf. 7o. 1803. 



Pale green, drying a dark brown; vegetative cells short, cylindrical, 35 55 

 in diam., one-half to twice as long; cell-membrane thin; fruiting cell aol 



swollen; copulation scalariform; zygospore spherical, dark brown. 1" in 

 diam., slightly punctate. 

 Lincoln, South Bend, Bellevue; quite common. PI VIII.. Pig. _. 



Zygiicma pectinatnm aiioiiialimi (Hass.j Kibohn. Alg. Sohles. 166. 18 - 



Tyndaridea anomala Hass. Brit. F. W. Alg. 16L 1845. 

 Zygnerna anomalum (Hass.) Cooke. Brit. F. W. Alg. 81. 1882. 



Vegetative filaments about 25 // broad, surrounded by a colorless -heat h t\\ ice 

 as broad; zygospore 26 \i in diam., olive brown, punctate. 



Common, often with the last. PI. VI II.. Fit;. •'!. 



3. SPIROttYKA Link in Nees Hor. Phys. Feed. 5. L820. 



Chloroplasts parietal, in one or several spiral or rarely Btraighl bands; 

 nucleus single; reproduction scalariform or lateral, zygospore always 



within one of the copulatiug cells. 

 Etymology: Greek cireipa, coil, and .curved. 



Section I.— Membrane folded in at the ends. 

 A. Chlorophyll bauds usually single. 

 * Membrane of zygospore smooth. 



Spirogyra toiuiis*iiiia (Hass.) Kuetz. Bp. Alg. 137. 1849. 

 Zygnerna tenuissimum Bass. Ann. a- Mag. \. II X . 1. 1842, 



Filaments usually scattered; diameter of vegetative oells 9 12 . 3 12 times 

 longer than broad; spiral single, making 3 5) . tur alum much 



swollen; zygospore oblong or elliptical, yellow or brown at maturity, 

 in diam. 

 Lincoln. PL VIII., Figs. 1 and 1 a. 



