208 FRESH-WATER ALG^ OF T II E UNITED STATES. 



Remarks. In 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 riid, more open, more broadly ovate, and less markedly piliferous than the 

 others. 



D. plumosa, (VAUCHER) AQARDH. 



D. filis ramisque primariis hyalinis, plernmqne J^"" = 0.00179" crassis; articulis diametro 

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

 strictis, fasciis chlorophyllosis angustis laete viridibus ; articulis inferioribus ramulorum dia- 

 metro ( Tsg'" 5*3"') sequalibus vel subduplo longioribus, paene torulosis, superioribus cylin- 

 dricis ad 5^3'" attenuatis, diametro duplo triplo-quintuplo longioribus, plerumque non pili- 

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

 pressis. (R. ) 



gyn. Dr. plumosa, (VAUCHER) AGARDII. RABENHORST, Flora Europ. Algarum, Sect. III. 

 p. 382. 



Hob. In rivulis et aquis quietis. 



Filament and primary branches hyaline, mostly fa'" = 0.001 T9" in diameter; articles as long aa 

 broad or one-balf 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 (ris"' sia"') or nearly twice as long, somewhat torulose, the upper ones cylindrical, 

 as small as 5^3"', two to five times longer than broad, mostly not piliferous ; fascicles of 

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



Remarks. 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. Billingsii, WOOD. 



D. valde gelatinosa ; filis et ramis primariis achrois ad 7!"^" crassis, sparsissime ramosis, 

 articulis diametro 2-6 plo longioribus, ssepe medio valde tumidis ; fasciis chlorophyllis dilute 

 viridibus, ssepe nullis aut subnullis ; ramulornm fascicnlis distantibus, late ovalibus vel late 

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

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

 conjunctis ; sporodermate crasso. 



Syn.D. Billingsii, WOOD, Proc. Am. Philos. Soc., 1869, p. 14a 

 Hab. In aquis qnietis, pfope Philadelphia. 



Frond very gelatinous, filament and primary branches attaining a diameter of 7 i</', ver 

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

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

 of branches distant, broadly 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. 



RcmarJcs. I found this plant about the middle of March, 1869, floating on tht 

 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 

 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. 



