FRESH-WATER ALG^ OF THE UNITED STATES. 203 



personally, and as being among the foremost students of American phanerogamic 

 botany. 



This' species is more nearly allied to S. minor than to any other of the European 

 forms, but differs from it very essentially in size and habit. It is always, as 1 have 

 seen it, except in very young plants, sparsely and mostly dichotomously branched, 

 and attains a very great length, at times probably exceeding the third of an inch. 

 The spore is mostly sessile upon the distal ends of the cells of the filament ; in all 

 such cases I have noticed that the cell upon which it was borne was divided in its 

 middle by a partition into two cells. Not unfrequently the spore is raised upon a 

 short branch. The male plants are attached to the female filaments generally in 

 the neighborhood of the sporangium, to which they sometimes fasten themselves 

 immediately. They are shortly stipitate, and composed of two cells. The mature 

 spore is transversely oval, now and then slightly triangular, and is nearly of the 

 color of burnt sienna. Its coat is thick, often slightly yellowish, and has on its 

 outer surface irregular punctations, looking like corrosions. These are not detach- 

 able, except when the ruptured spore is more or less completely emptied of its 

 contents. The sporangium closely invests the spore, and when the latter is matured 

 undergoes a circular division, so that the top falls off and allows the spore to escape. 



Fig. 6 c, pi. 16, represents a portion of a filament, magnified 260 diameters, 

 with a young sporangium and young male plants attached ; 6 h, represents a very 

 young plant, magnified C60 diameters. Fig. 6 a, was taken from a mature plant, 

 and shows the mature spore. Fig. 6 e, shows in outline a sporangium and male 

 plants attached ; whilst 6 d, was drawn from a sporangium which had perfected 

 its spore and undergone the natural dehiscence. 



Family OHROOLEPIDE^. 



Algae aerese, aureo-, aurantiaco- vel rubro-fuseo-colorate, siccatfe saepe cause. Fila varie ramosa, 

 cytiodermate crasso vel subcrasso, firmo, subcartilagineo praedita, in pulvinulos minutos vel in stra- 

 tum tenue aut incrftssato-tomentosum densissime aggregatavel implicata. Cytioplasma oleosum vel 

 granulosum, aut rubellum, aureum, aut flavo-fuscum, interdum viride tinctum, post mortem plerum- 

 que expallescens. Propagatio fit zoogonidiis. 



^rial algae. Golden orange, or reddish fuscous, often grayish when dried. Filaments variously 

 branched, furnished with a thick, or thickish, subcartilaginous cytioderm, densely aggregated into 

 minute cushions, or a thin or tomentosely thickened stratum. Cytioplasm granular or containing 

 oily particles, reddish-golden, or yellowish-fuscous, sometimes tinged with green; after death often 

 colorless or nearly so. Propagation by zoospores. 



Eemarks. — The plants of this family are so different from the others of the 

 order, that it is a matter of considerable doubt whether or not they should be 

 classified with them. They rarely possess distinct, well-pronounced chlorophyl, 

 and form mats or strata of some shade of reddish, grayish, or brownish, so that 

 they are very different in appearance from the other Gonfervacece. 



I do not think their position can be certainly fixed until their life-history has 

 been more fully developed. In assigning them this place I have simply followed 

 Prof. Rabenhorst. 



