198 FRESH-WATER A L G JE OF THE UNITED STATES. 



infra medium posito ; oosporis globosis, oogonii lumen haud replentibus, superfieie lineis 

 elevatis spiralibus quatuor instrueta ; antheridiis bicellularibus (inturdum tricellularibus ?). 



Diam. Spor. 5 >y=.002". 



Syn. CEdogonium Huntii, WOOD, American Naturalist, 1868. 



Hob. In aquario meo. 



Filaments mostly produced into a long apical seta; oogonia mostly single, globose, sometimes 

 somewhat hexagonal, somewhat tumid in the middle, the lateral pore placed below the 

 middle ; oospore globose, not filling the cavity of the spore case, its surface with four spiral 

 elevated lines or ridges ; antheridia bicellular (sometimes triccllular ?). 



Remarks. This little plant appeared in my aquarium some years since, forming 

 a delicate fringe upon the various aquatic plants growing therein. Its color is a 

 bright yellowish green, deepening to a very dark green in cells which are crowded 

 with granular protoplasm. The filaments vary very greatly in size, the largest I 

 have seen were $%$ of an inch in diameter. They are provided with long, termi- 

 nal seta, which are much more universally present than in any of the other species 

 I have met with. The first step in the formation of a spore is the emptying of a 

 cell into its distal neighbor, so that each spore case is placed at the end of an empty 

 cell. These sporangia may be single or they may be in series of two or more, 

 separated only from one another by the eruptive cells just spoken of. The color 

 of the mature spore is a very dark reddish-brown. The antheridia is bicellular, 

 slightly curved, somewhat stipate, with a distinct foot. Its most common position 

 is on the vacated cell just below the spore case. The zoospores, as I have seen 

 them, are always globose. 



I have named this species after my friend, Dr. J. Gibbons Hunt, a well-known 

 microscopist of this city, to whom I am greatly indebted for aid in my earlier 

 microscopic studies. 



Fig. 2, pi. 17, represents different forms and parts of this plant. 2 a shows 

 the end of a filament and the long seta-like lip. 2 b was taken from two cells, 

 one of which had just undergone division, and shows very plainly the method of 

 procedure ; lying as it were between the cells, and bearing the end of the lower 

 one upon it, is the new little cell. Fig. 2 c represents a fertile filament with two 

 mature spores and one not fully grown. Fig. 2 d was drawn from a filament just 

 forming a spore, and shows the male plant in situ. Fig. 2 e represents a male 

 plant (magnified some 1300 diameters) with the outer terminal cell scarcely more 

 than a primordial utricle. The contents of the lower cell were in a state of in- 

 tense motion; and the arrows are meant to indicate the directions of the currents. 

 Fig. 2 / represents a portion of a filament with a zoospore just escaped and still 

 quiescent. 



A. echinata, WOOD (sp. nov.) 



A. valde elongata ; articulis diametro 6-14 plo longioribns; oogoniis globosis, plerumque do- 

 pressis, ad .0014" crassis; oosporis oogonii forma et cjus lumen replentibus, valde aculeatis; 

 poro laterale supra medium posito ; antheridiis bicellularibus ? 



Diam. Spor. r5 VW"= .001". Cell. ^"^TS" = .00033" .0005". 

 Hob. In stagnis, Alleghany Mountains. 



