FRESH-WATER ALG^ OF THE UNITED STATES. 215 



measurements given above are copied from Prof. Rabenhorst's work. My specimen 

 agrees well with it. 



P. mag^nificum, Wood. 



P. cellulis globosis vel subglobosis, ssepe nonnihil polygonis et in massam indefinite expansam 



confiuentibus ; cytioplasmate purpureo, granulate ; cytiodermate crasso, baud lamelloso. 

 Diam.—Cell cum. tegum. ^^I^^— s^VIttt. Tegum. ^^^^^—^^^^^. 

 Syn. — P. magnificum, Wood, Proc. Am. Philos. Soc, 1869, p. 144 

 Hob. — In terra humida, Texas ; Prof. Ravenel. 



Cells globose or subglobose, often somewhat polygonal and conjoined into an indefinite mass ; 

 endochrome purple, granulate ; cell wall thick, not laminate. 



Remarks. — This species, which was collected in Texas by Prof. Ravenel, growing, 

 I believe, on wet sand, is very distinct from the European plant, differing essenti- 

 ally in size and form. In some instances the cells have a greenish tint, but this is 

 possibly owing to immaturity, as such cells seem smaller than others. The whole 

 mass to the eye has a very rosy purple tint, and although under the microscope it 

 appears much darker and more purple, yet it often retains some of the roseate hue. 

 At the edges of the masses the dark-reddish color often gives way to a very decided 

 greenish tint, presenting an appearance which is very well represented in the 

 drawing of the preceding species, in M. Mengehini's Monographia Nostochinearum 

 Italicarum, cfec, Memoire della Reale Academia delle Scienze di Torrino. The cells 

 are often closely united by their thick coats into a very coherent mass. With the 

 ordinary cells I have occasionally seen other larger ones, of an orange color, with 

 very thick walls. Are these resting spores ? 



Fig. , pi. 19, represents single cells of this plant magnified 760 diameters. 



Family CHANTRANSIACE^, 



Thallus filamentosus. Fila articulata, e cellularum serie unica formata, ramosa, stricta, nuda, 

 raro passim corticata, rami superne fasciculatim ramellosi ; articuli cylindrici. Cytioderma, homo- 

 geneum, maxirae hyalinum. Cytioplasma homogeneum, plerumqne purpurascens. Propagatio fit 

 polysporis immobilibus, ovalibus, in ramellorum apice vel lateraliter formatis, corymboso aggregatis. 

 Antheridia subglobosa, terminalia. Tetraspora raro observatsB. 



Thallus filamentous. Threads articulate, formed of a single series of cells, branched, straight, 

 bare, rarely here and there articulate ; branches above fasciculately branched ; joints cylindrical. 

 Cytioderm homogeneous, mostly hyaline, cytioplasm homogeneous, mostly purplish. Propagation 

 by immovable oval polyspores formed on the ends of the branches or laterally and corymbosely 

 aggregate. Antheridia subglobose terminal. Tetraspores rarely observed. 



Genus CHANTRANSIA, Fries. 



Familise genus unicum. 



The only genus of the family. 



C. expansa, Wood. 



C. cffispitosa, in lapide stratum saturate violaeeo-purpurenm lubricum, indefinite expansura, 

 fprmans ; fills purpureis, raodice ramosis, fere 2 lineas longis et ramis plerumque strictis et 

 rectis, sape elongatis ; ramulis fertilibus brevibus, ascendentibus ; articulis diametro 3-8 plo 



