FRESH-WATER ALG^E OF THE UNITED STATES. 125 



adjoining ends of the next joint being similar, tliese projeetions being produced ]>y an annular 

 grooved rim. L. t.^l/_GOO". B. •^^\^"—^^\^". (Archer) 



Genus BAMBUSINA. 



Cellulffi oblongo-orculiformes, in filamenta articulata nodosa dense conjunctse, medio vitta trans- 

 versa carinis duabus annuliformibus liniitata instrueta;, itaque superne et interne bidentatie, i'ruute 

 circulares, supra et infra dente unieo pronunente. (R.) 



Cells oblong-oreuliform, densely united into an articulate uodose filament, surrounded by two 

 median bands. 



B. Brebis§onii, Ktz. 



B. filameutis nodoso-articulatis ; cellulis diametro duplo longioribus. (R.) 



Diam.—O.OOOTr'— 0.00092". (R.) 



Syn. — B. Brebissonii, KiJTZiNa. Rabenhorst, Flora Europ., Algarum, Sect. III. p. 152. 



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

 Biiiley. 



(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 unchantred. 

 1 " 



L. TsW- B. — '- 



Remarhs. — Tlie 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 

 TiVo of ^^1 "^*^^^ "^ diameter. 



Genus DIDYMOPRIUM. 



Cellulse oblongo-ellipticae, modice compress^, ancipites, angulis porrectis inciso-bidcntatis, in fila- 

 menta articulata biconvexa et torta sine isthnio arete conjunct^, ct in vagina mucosa inclu.s;p. 

 Cytioplasma chlorophyllosa cellulas a fronte cruciatim disposita, cujus crura e laminis duabus jiarie- 

 talibus divergentibus granum amylaceum unicum 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, cj'tio- 

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

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



D. Grevillii, Ktz. 



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

 Z)iam.0.0024"— 0.0031." (R.) 



Syn. — D. Grevillii, KCtzing. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 153. 

 Eab. — 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, funned 

 within one of the two conjugating joints, the endochrorae 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. 



