208 



FRESH-WATER ALG^ OF THE UNITED STATES. 



Eemarhs.—ln this form there are almost always numerous little clusters of branch- 

 lets, growing immediately from the main stem or large branches; such clusters are 

 more rigid, more open, more broadly ovate, and less markedly piliferous than the 

 others. 



D. plumosa, (Vauchee) Aqardh. 



D. filis ramisque primariis hyalinis, pleminqne -5V'" = 0.001'79" crassis; articuHs diametro 

 sequalibus vel dimidio brevioribus, rarius paulo longioribus, geniculis vix aut modice con- 

 strictis, fasciis cblorophyllosis angustis Isete viridibus ; articulis inferioribus ramulorura diar 

 metro ( t^'"— 5J3'") sequalibus vel subduplo longioribus, psene torulosis, saperioribus cylin- 

 dricis ad ^i^'" attenuatis, diametro duple tr.iplo-quintuplo longioribus, plerumque non pili- 

 feris ; ramulorum fasciculis dense ramellosis, elongatis, acute lanceolatis, erecto-subap- 

 pressis. (R.) 



Syn. Br. plumosa, (Vaucher) Agardh. Rabenhorst, Flora Europ. Algarum, Sect. III. 



p. 382. 



JJijtb. — In rivulis et aquis quietia 



Filament and primary branches hyaline, mostly^V" = 0.001Y9" in diameter; articles as long as 

 broad or one-half shorter, rarely a little longer, scarcely or slightly constricted at the joints, 

 chlorophyl fascia bright green, narrow ; lower articles of the branches about as long as 

 broad (^^5'" — ^W) or nearly twice as long, somewhat torulose, the upper ones cylindrical, 

 as small as ^jg'", two to five times longer than broad, mostly not piliferous ; fascicles of 

 branches densely, branched, elongate, acutely lanceolate, actually subappressed. 



BemarJcs,. — I have found a Draparnaldia frequently, which I believe to represent 

 the European D. plumosa.^ As I have preserved, however, no specimens or 

 descriptions, I have simply copied the description of Prof. Rabenhorst. 



D. Billing^sii, Wood. 



D. valde gelatinosa ; filis et ramis primariis achrois ad yf^^" crassis, sparsissime ramosis, 

 articulis diametro 2-6 plo longioribus, seepe medio valde tumidis ; fasciis chlorophyllis dilate 

 viridibus, saepe nullis aut subnullis ; ramulorum fasciculis distantibus, late ovalibiis vel late 

 triangularibus, alternantibus vel oppositis vel triplice verticeJlatis, sparse ramosis, patentissi- 

 mis ; ramulis pilis longissimis robustis terminalibus instructis ; oosporis globosiB, moniliforme 

 conjunctis ; sporodermate crasso. 



Syn. — D. Billingsii, Wood, Proc. Am. Philos. Soc, 1869, p. 143. 



Hob. — In aquis quietis, prope Philadelphia. 



Frond very gelatinous, filament and primary branches attaining a diameter of ^JV'> ^^^T 

 sparsely branched, their articles 2-6 times longer than broad, often very much swollen in 

 the middle ; chlorophyl band light green, frequently almost or entirely wanting ; fascicles 

 of branches disfant, broa'dly oval or triangular, alternate, opposite, or in whorls of three, 

 very open ; ultimate branchlets terminating in a long, robust, hyaline hair ; resting spores 

 globose, with thick walls, arranged in long moniliform sometimes branched filaments. 



Remarhs.—l found this plant about the middle of March, 1869, floating on the 

 surface of a little pool in the woods near Chelten Hills, a few miles north of 

 Philadelphia. To the naked eye it appears as a gelatinous mass, resembling a 

 Tetraspora, but when closely examined this translucent jelly is seen to be filled 

 with rather distant greenish points, which are the little clusters of branches. The 

 largest specimens I have seen had attained a length of nearly two inches. The 

 filaments are very transparent and have the branches placed at long intervals. 



