166 FllESII-WATKU ALGAi OF THE UNITED STATES. 



for the very great thickness of the walls of the spore. There are two very appa- 

 rent coats separated by a thin not very evident one. The outer is the thickest; 

 it is verv thick, firm, and nearly colorless. Tiie inner coat is of a decided orange- 

 brown. The parent-cells which give origin to these spores are slightly enlarged 

 in diameter. Sometimes the spores, instead of being elliptical, are irregular in 

 shape. 



Fi"-. 3 a, pi. 14, represents a sterile filament, magnified 250 diameters; fig. 3, a 

 mature spore, magnified 4:50 diameters. 



Sp. iusignis, (IIassali.) Ktz. 



Sp. articulis sterilibus diametro 5-14 plo longioribus ; fasciis 2 (rarius 1-3), laxe spiralibus, 

 aiif^ustis, ci-euatis; articulis fructiferis nonniiiii tuniidis ; cytiodeniiate utroque fiue rcplicatu 

 vt'l pi-otuiiso ; zygosporis rubido-bruuueis, ovato-ellipticis. 



Diam.—O.OOli)". 



Syn. — Zyrjnema insigne, Hassall, Fresh-Water Algfe, p. 440. 



Sjiirogtjra iiisitjiiis, (Hassall) Kuxzinu. ItABEXHORST, Flora Europ. Algarum, Sect. 

 III. p. 235. 

 Sab. — In stagui.s, in'ope Pliiladfliiliia. 



Sterile joints 5-14 times longer than broad ; ehlorophyl filaments mostly 2 (rarely 1-3), la.xly 

 spiral, narrow, crcnate ; fertile joints somewhat enlarged; cytiodcrin at each end folded iu 

 or produced ; zygospores reddish-brown, ovate elliptical. 



Eemark. — Fig. G, pi. 16, represents this species. 



b. Cytioderma celhdae fine nee pi'olensum nee repllcalam. 



Cytioderm not infolded in the end of the cell. 

 * Fasciss spirali unicse {raro duse). 

 ChloropJiyl band single {rarely two). 

 Sp. longata, (Yaucii.) Ktz. 



Sp. dense c;espitosa, late luteolo-viridis, valde lubrica; articulis sterilibus diametro 2-U plo 

 longioribus, fertilibus sajpe tumidis abbreviatis ; fascia spirali lata, dentata ; anfractibus sub- 

 laxis 2-5 ; zygosporis ellipticis. 



Diam.— 0.001". 



Syn. — GonjiKjala lungata, Vaucher, Ilistoire dcs Conferves d'Eau douce, p. 71- 



Sp. longata, (Yauch.) KiJTziNO. Kabenhoust, Flora Europ. Algarum, Sect. III. p. 23S. 



Hab. — In stagnis, prope Philadelphia; Wood. Khode Island; (S. T. Olney) Thwaites. 



Densely CiBspitose, bright yellowish-green, very slippery ; sterile joints 2-6 times longer than 

 broad; fertile articles swollen, often abbreviate; ehlorophyl filaments broad, dentate; turns 

 of the spiral somewhat loose, 2-5 ; zygospores elliptical. 



Remarlcs. — According to Prof Ilabenhorst, this species attains in Europe a 

 diameter of .0011" and the cells a length of 8 times their breadth. The same 

 authority also describes the fertile cell as being either not swollen, or moderately 

 so (" ant non ant modice tumidis"). In all the specimens of our American forms 

 which I have seen, the sporangial cells are very decidedly swollen. 



I'ig- 4, pi. 14, represents portions of sterile filaments, magnified 250 diameters, 

 and fig. 4 a, a part of a fertile pair of filaments containing immature spores enlarged 

 260 diameters. 



