20 THE FLORA OF NEBRASKA. 



Microcolon* vaginatus (Vauch.) Gomoxt Monogr. Oscil. Ann. So. Nat, Bot. 

 7. XV., 355. 1803. 

 Oscillatoria vaginata Vaucher Hist. Conf. 200. 1S03. 

 mcrocoleus terrestris Desmazieees 1. c. 



Stratum more or less expanded, deep blue-green, changing to olive and then 

 to a brownish-red, membranaceous, mucilaginous; filaments equal, col- 

 lected in filiform fascicles, sometimes much elongated, extending in a 

 penicillate manner from the opening of a common sheath, attenuate and 

 capitate. 3'., 7 a broad; articulations equal to twice the diameter in length, 

 frequently granular at the articulations. 

 On damp earth, etc., in greenhouses at the University. PI. II., Fig. 21. 



«. SCHIZOTHKIX Kuetz. Phyc. Gen. 230. 1843. 



Filaments few in a sheath, somewhat loosely aggregated; articulations often 

 longer than the diameter of the filament, never shorter; apex of the fila- 

 ment straight, sometimes attenuate, never capitate; membrane of the 

 apical cell not thickened above; sheath hyaline, fuscous or purple, firm, 

 lamellose, acuminate at the apex. 

 Etymology: Greek <7,i<«, cut, and dpi!;, hair. 

 Schizothrix calcicola (Ag.) Gomont Ann. Sci. Nat. Bot. 7, XV., 307. 1892. 

 Oscillaria calcicola Ag. Disp. Alg. Suec. 37. 1812. 

 Leptothrix calcicola Kuetz. Phyc. Gen. 200. 1843. 



Filaments dilutely aeruginous, not constricted at the joints, 1-1.7 //, broad; 

 articulations longer than the diameter of the filament, 2 3 to as much as 

 Cm long; sheath firm, subcartilaginous, apex acuminate, cylindrical, en- 

 closing one or two or rarely several filaments. 

 In greenhouse at the University. PI. II., Fig. 19. 



Sob-Fam.— Lyngbyeae. Filam9nts solitary in the sheath. 



:{. OSCILLARIA Bosc. in Bory Diet. CI. I., 594. 1800. 



Filaments oscillating, cylindrical, free, without sheaths or occasionally with 

 a delicate sheath, fragile, usually involved in a colorless mucus, slightly 

 or not at all constricted at the joints; apex often attenuate, straight, or 

 curved. 



Etymology : Latin oscillare, to swing, oscillate. 



Oscillaria tenerrima Kuetz. Tab. Phyc. 1 1. 38. 1819. 



Solitary or associated in fascicles, filaments straight, indistinctly articulate, 

 joints about equal to the diameter in length, ends somewhat acute, 

 slightly bent, cell-contents pale blue-green or olive, homogeneous or 

 finely granular, filaments 1.8-2.5 \i in diam. 



In ditches and ponds among other algae. PI. II, Fig. 18. 



Oscillaria splcmliua Greville Flor. Edin. 305. 1824. 

 Oscillaria gracillima Kuetz. Phyc. Gener. 181. 1843. 



Pale aeruginous ; filaments straight, curved, or sometimes coiled, solitary or 

 forming a thin membranaceous stratum, obtusely rounded at the apex 

 and often bent, 2J-3.5 // in diam. ; cell-contents light aeruginous; articu- 

 lations not always distinct, about as long as wide. 

 On basin of artesian well (salt), Lincoln. 



