196 FRESH-WATER ALG^E OF THE UNITED STATES. 



only seen the latter when more or less completely emptied, but, judging from the 

 relative sizes, there must be several. In a cell containing a single spermatozoid, that 

 body moved about freely, and at last escaped, apparently through 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 was 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 a, pi. 18, represents a young female plant; 1 6, a fertile plant with imma- 

 ture spores. 1 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. Androsporce in plantis femineis ortse ; postea hanc affixse et in antheridiis se formant. 



Gynandrous. Androspores arising in tbe female plant ; after affixing themselves to this and 

 developing into antheridia. 



A. multispora, WOOD. 



A. oogoniis singulis, vel binis vel ternis continuis, globosis instructa; poro laterale distale; 

 oosporis globosis, oogonii lumen replentibus ; antheridiis plerumque pluribus, plauta feminea 

 insidentibus, cellula inferiore multo majoribus. 



Syn. Oedogonium multispora, WOOD, Proc. Amer. Philos. Soc., 1869, 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, CEdogon. 

 Rothii and (E. depressum, 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, with an empty basal cell in one 

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

 formed spermatozoids. The small arrows indicate the direction of cyclotic 

 currents. 



A. mirabilis, WOOD. 



A. rare setigera ; articnlis diametro 2-8 plo longioribus ; oogoniis plerumque singnlis, rare 

 geminis, nonnihil ovatis, infra latis sed supra contractis et medio tumidis ; poris lateralibus 

 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 ; spermatozoideis singulis et geminis. 



Diam. Artie, veget T; a nr "_ 7 i3/=.o004" 0017". Spor. T ^"_ 7 f<>V'.0024" 02 ?"- 

 Syn. (Edogonium mirabile, WOOD, Proc. Amer. Philos. Soc., 1869, p. 142. 

 Hab. In rivulis quietis, prope Philadelphia. 



