FRESH-WATER ALG^ OF THE UNITED STATES. 1G5 



cells. I have never been able to identify an entirely sterile filament of this species; 

 the measurements and description of the sterile cells were taken from infertile cells 

 in filaments, which in other places had produced spores. 



Fig. 2, pi. 14, represents a fertile filament, magnified "iCiO diameters. 



B. CONJUQATIO SCALARIPOEMIS (SpIROGYBA VERA). 



a. Cij/iodermale lUroqiie Jine prolensum et rcplicatum. 

 a. Gytiodcrm folded in at the ends. 



* Fascia spiralis iinica. 



* Spiral filament single. 



Sp. Weberi, Ktz. ? 



Sp. saturate viridis, lubrica ; articulis vcgetativis diamotro 3-20 plo longioribus; fructiferis 

 nonnihil iuflatis; fascia dentata, ploniiiKiue uiiica sed lasciis diialtus in quavis cillula; s])ira! 

 aufractibus 3-8; cytiodermate plerumque uti'oquo fiiiu prutcuso et replicato ; zygosporis cllip- 

 ticis. 



I>iam.—Aviic. stcril. j-f-g-^"—j^%^" = .0()0S"—.0QV2". 



Syn. — S. Weberi, Kutzino. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 233. 



Eab. — In stagnis, prope Philadelphia. 



Deep green, slippery; sterile joints 3-20 times longer than broad; fertile joints not swollen ; 

 ehlorophyl filaments mostly single, but sometimes two in certain cells, dentate ; turns of the 

 spiral 3-8 ; eytioderm protruded or infolded at the oud.s ; zygospores elliptical. 



Remarhs. — This species, which is abundant around Philadelphia in stagnant 

 ditches, I have found fruiting in the month of April. The number of spirals fre- 

 quently varies even in the same filament. The infolding of the walls at the end 

 of the cells is very often wanting in the fertile cells and occasionally is absent from 

 one end of an ordinary vegetative cell. The American form agrees pretty well 

 with the European, but is, however, larger, and also attains in its cells a greater 

 proportionate length and has more turns of its ehlorophyl spirals. The lower 

 limits of the American form are, however, so overlapped l)y the upper limits of the 

 European, that it seems to me they must be considered identical. 



Fig. 19, pi. 12, represents a pair of fertile filaments of this species, magnified 

 260 diameters; 19 «, part of a sterile filament, magnified '2G0 diameters; 19 A, out- 

 line of a couple of fertile cells, magnified 260 diameters. 



Sp. protecln, Wood. 



Sp. saturate viridis, lubrica; articulis sterilibus diametro 6 plo longioribus; s])oriferisvi.\ tuniidis; 



cytiodermate utroque fine protenso et replicato ; fascia unica; aufractibus G; sporis oblongis 



vel ellipticis : meuibrano crassissimo. 

 Diam.—Ari. steril. ^ij/ = .00146" ; spor. lat. T-igg"_7i-?/ = .00133"— .OOIG" long. ^^^" 



= .0033". 

 Syn. — Sp. proleeta, Wood, Prodromus, Proc. Am. Philos. Soc. 1869, p. 131. 

 Sp. deep green, slippery ; sterile joints 6 times longer than broad ; fertile cells scarcely swollen ; 



cell wall folded in at the ends; ehlorophyl band single ; turns 6 ; spores oblong er e!lii)tical, 



spore wall very thick. 



JRcmarl-f:. — I found this species in the latter part of April fruiting in a ditch 

 in a meadow a little south of the mouth of Wissahicon Creek, near this city, 

 and as late as the 25th of May in the "neck" below the city. It is remarkable 



