FRESH-WATER AliGM OF THE UNITED STATES. 125 



adjoining ends of the next joint being similar, these projections being produced by an annular 

 grooved rim. L. ^^^^^"—6Q0". B. t-^V^"— tAt"- (Archer) 



Genus BAMBUSINA. 



Cellulae oblongo-orculiformes, in filamenta articulata nodosa dense conjunctaa, medio vitta trans- 

 versa carinis daabus annuliformibus limitata instructse, itaque superne et inferne bidentatse, fronte 

 circulares, supra et infra dente unico prominente. (R.) 



Cells oblong-orculiform, densely united into an articulate nodose filament, surrounded by two 

 median bands. 



B. Br6bissonii, Ktz. 



B. filamentis nodoso-articnlatis ; cellulis diametro duplo longioribus. (R.) 



Dmm.— 0.00017"— 0.00092". (R.) 



Syn. — B. BrSbissonn, Kutzinq. Rabenhorst, Flora Europ., Algarum, Sect. III. p. 152. 



Bab. — South Carolina. (Ravenel) Wood. South Carolina ; Georgia ; Florida ; Rhode Island. 

 Bailey. 



(Didymoprium Borreri, (Ralfs)) Joints inflated, barrel-shaped, longer than broad, without a 

 thickened border at their junction ; angles bicrenate, crenatures rounded ; transverse view 

 circular ; sporangium elliptic, formed within the (for some time) persistent extensions from 

 the conjugating joints, which do not previously break up into single joints, but couple, still 

 united in the filament, in a confused or zigzag manner, some of the joints remaining unchanged. 

 1"- vW- ^- TijW'- 



Remarhs. — The specimens which. I have seen agree well with the descriptions, 

 except in regard to size; some of the cells which I measured were more than 

 TfV? °^ *^ ^^^^ ^"^ diameter. 



Genus DIDYMOPRIUM. 



Cellulse oblongo-ellipticse, modice compressae, ancipites, angulis porrectis inciso-bidentatis, in fila- 

 menta articulata biconvexa et torta sine isthmo arete conjunctae, et in vagina mucosa inclusae. 

 Cytioplasma chlorophyllosa cellulae a fronte cruciatim disposita, cujus crura e laminis duabus parie- 

 talibus divergentibus granum amylaceum uuicum involventibus formantur. 



Cells oblong-elliptical, moderately compressed, two-edged, with the produced angles incisely-biden- 

 tate, closely united into a biconvex and twisted filament, which is inclosed in a mucoid sheath, cytio- 

 plasm so placed as to be cruciate when viewed from the front (end), each crus composed of two 

 parietal divergent lamina, each of which contains a single starch granule. 



D. C}reTiIlii, Ktz. 



D. cellulis oblongis diametro duplo brevioribus, saturate viridibus. (R.) 



Diam.0.0024"— 0.0031." (R.) 



Syn. D. Orevillii, KtJTZiNG. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 153. 



^a6.— Georgia, South Carolina ; Bailey. Pennsylvania ; Wood. 



Sheath distinct ; joints broader than long, with a thickened border at their junction ; angles 

 bidentate ; teeth angular ; transverse view broadly elliptic. Sporangium orbicular, formed 

 within one of the two conjugating joints, the endochrome passing over from one by a narrow 

 connecting tube produced between the otherwise, but little altered, broken-up single joints. (A.) 



Remarh. Fig. 13, pi. 12, represents the end view of a broken filament of this 



species. 



