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



V. v< hilina. AG. 



V. tballo repente, raraulis erectis, numerosis, fastigiatis, in caespitem velutinum laete viridem 

 iutricatis ; oogoniis lateralibus singulis, globosis, sessilibus, antheridio paulo longiore unico 

 subulate leviter incurvato consociatis (R.) Species mihi ignota. 



Diam. Oogonii 0.0023" 0.0027". (R.) 



Syn. V. velutina, AGARDH. RABENHORST, Flora Europ. Algarum, Sect. III. p. 274. 



Hab. Salem, North Carolina; Schweinitz. Common at West Point, New York; Waterville, 

 Maine; Culpepper Co., Va. ; Bailey. 



"Filaments exceedingly tough, interwoven into a dense, velvety, green stratum, pellucid below 

 and creeping over the mud; branches near the extremity erect, fastigiate, and more or less 

 crooked; vesicles solitary, globular, on short lateral peduncles." Carmichael. 



V. geminata, (YAUCH.) DE CANDOLLE. 



Y. obscure vel sordide viridis, in casspites dense intricata; thallo capillari, tenaci, dichotomo ; 

 oogoniis duobus (rarius 1 vel 3),ovatis vel obovatis, oppositis, distincte pedunculatis, antheridio 

 intermedio subulato, plus minus recurvo ; oosporis inaturis fusco-maeulatis, sporodermate 

 achroo e stratis tribus composite involutis; sporangiis in eodem vel proprio thallo, cyathiformi- 

 ampliatis truncatis et angulato-cornutis. (R.) 



Syn. V. geminata, (YAUCH.) DE CANDOLLE. RABENHORST, Flora Europ. Algarum, Sect. III. 

 p. 269. 



Hab. In stagnis, prope Philadelphia; Wood. 



Obscure or sordid green, densely interwoven into a turfy mass; thallus capillary, tenacious, 

 dicbotomous ; oogonia two (rarely 13), ovate or obovate, opposite distinctly pedunculate, 

 antheridia intermediate, subulate, more or less recurved ; oospores at maturity spotted with 

 fuscous, their coat transparent and composed of three strata ; sporangia in the same or a sepa- 

 rate thallus swollen cup-shaped, truncate and horned at the angles. 



Remarks. I have found this species in fruit but once, then it grew in a ditch 

 below the city. Not having mounted any of it, nor having written a description 

 of it at the time, I have been forced to simply copy that of Prof. Rabenhorst. 



V. polymorpha, WOOD. 



V. in caespites dense intricata ; thallo capillari, tenui ; antheridiis corniculatis ex ramuli lateralis 

 apice formatis ; ramulis fertilibus interdum et oogoniis et antheridiis instructis, interdum 

 antheridiis solum ; oogoniis plerumque geminis, iuterdum singulis, globosis vel ovatisi saepe 

 breve rostratis, plerumque distincte pedunculatis sed rarius sessilibus ; oosporis enormiter 

 subglobosis vel ovatis; sporodermate achroo, e stratis duobus composite. 



Syn. V. polymer pha. WOOD, Prodromus, Proceedings Amer. Philos. Society, 1869, p. 140. 

 Hab. In aquis, prope "Buffalo Bayou," Texas; (Ravenel.) 



Csespitose ; thallus fiair-like, thin ; antheridia corniculate, formed of the apex of lateral branches ; 

 fertile branches sometimes furnished both with oogonia and antheridia, sometimes with 

 antheridia alone ; oogonia sometimes single but mostly in pairs, occasionally shortly rostrate, 

 generally distinctly pedunculate but sometimes sessile; oospores irregularly subglobose or 

 ovate, surrounded by a transparent double spore coat. 



Remarks. This species was collected by Prof. Ravenel near the city of Houston, 

 Texas. As I received the mass, it was labelled as being obtained from "a shallow 

 slimy pool formed by drippings from the side of a ravine near Buffalo Bayou." 

 The species probably grows in the water, evidently forming turfy mats. It is 



