1<)G FRESH -WATER A L G .E OF THE UNITED STATES. 



only seen tlio latter wlifu iiioro or loss conipktely emptied, but, judging from the 

 relative sizes, tliere must be several. In a eell containing a single spermatozoid, that 

 body moved about freely, and at last escaped, apparently tlirough an orifice in the 

 end wall of the cell. It made two attempts before getting out, and during its 

 passage was distinctly constricted in the middle. It resembled in appearance an 

 ordinary zoospore, but Avas of course much smaller, and was nearly devoid of color, 

 having but a slight greenish tint. I found this species growing abundantly in the 

 stagnant ditches of the Neck, below the city. 



Fig. 1 «, pi. 18, represents a young female plant; 1 h, a fertile plant with imma- 

 ture spores. I c was taken from the supposed male plant alluded to in the text. 

 The latter figure is magnified 450 diameters, the others 250. 



Genus ANDROGYNIA. 



Gynandra. Androsporic in plantis fcmincis ortaj ; postea Lane afE.xa! et in antheridiis se formant. 



Gynandrous. Androsporcs arising in the female plant ; after affixing themselves to this and 

 developing into aiithcridia. 



A. llliilti>i|)ora, Wood. 



A. oogoniis singulis, vel binis vel ternis eontinuis, globosis instructa ; poro laterals distale; 

 oosporis globosis, oogonii lumen replentibiis ; antheridiis plerumque pluribas, plauta femiuca 

 insidentibus, cellula inferiore multo majoribus. 



Syn. — Oedogonium muUispora, Wood, Proc. Anier. Philos. Soc., 1809, p. 141. 



Hab. — In stagnis, prope Philadelphia. 



Oosporangia single or bi- or triseriate, globose with a distal lateral pore ; oospore globose, 

 about the same size as the sporangial cavity; antheridia bi- or tricellular, curved, with the 

 lower cell much the largest, generally adhering in considerable numbers to all parts of the 

 female plant. 



Remarks. — This species differs from its nearest European congeners, CEdagon. 

 Bothii iind CE. de^jrcssum, very markedly in the bicellular antheridia. I have never 

 seen the spermatozoids actually emerging from their mother-cell, but have seen in 

 the terminal antheridial cell a pair of oval bodies, which I took to be those bodies. 

 Fig. 3, pi. 17, was taken from a filament of this species magnified 500 diameters. 

 It shows spores in different stages of maturity, Avith an empty basal cell in cue 

 case, and in the others without. Also male plants, one of tliem containing partially 

 formed spermatozoids. The small arrows indicate the direction of cyclotic 

 currents. 



A. iiiii'aliili!«, Wood. 



A. rare setigera ; articulis diamotro 2-8 plo longioribus ; oogoniis plerumque singulis, rnrc 

 geminis, nonnihil ovatis, infra latis sed supra contractis ct medio tumidis ; pons lateralUms 

 duobus supra medium positis ; oosporis aut late ovalibus aut subglobosis ; sporodermate baud 

 signato ; antheridiis plerumque bicellularibus, interdum tricellularibus, plerumque in filo 

 vegetativo infra oogonium aut in oogonio insidentibus ; spermatozoidois singulis et geminis. 



Diam.—Artic. veget t-.V— THtj"=-0004"— 0017". Spor. t>§j"_7|»/. 0024"— 0027". 

 Syn.—CEdvgonium mirabile, Wood, Proc. Amer. Philos. Soc, 18G9, p. 142. 

 Hah. — In rivulis quictis, prope Philadelphia. 



