64 BATEACHOSPERME^. 



gelatinous ; whorls of ramelli globose, distinct, the branches resembling strings of beads. 

 Kiitz. Sp. Alg. 1, p. 535. Harv. Man. Ed. 1, p. II9. Hass. Brit. Fr. Wat. Alg. 

 p. 108. Conferva gelatinosa, Dillw. Conf. t. 32. E. Bot. t. 689. 



Hab. On stones, &c. in running streams and wells of fresh water. New York, Prof. 

 Bailey, Mr. Calverley. Virginia, Mr. Jackson. Alabama, Prof. Tuomey. South 

 Carolina, Mr. H. W. Ravenel. Michigan, Dr. A. Gray. (v. v.) 



Fronds densely tufted, gelatinous, capillary, irregularly much branched, decompound, 

 the branches tapering to their extremity, beset with short tapering ramelli, which are 

 very patent and once or twice divided. All the branches and ramuli are raoniliform, 

 and are composed of a filiform cylindrical axis ; set at short intervals with very dense, 

 globose whorls of multipartite, dichotomous ramelli. The axis is formed of an articu- 

 lated monosiphonous filament, externally coated with a sheath of closely-placed, cohering, 

 longitudinal, parallel, articulated, very slender filaments, derived from the bases of the 

 whorled ramelli, and developed along the internodes from above downwards. The 

 ramelli are excessively branched, and composed of short cells much constricted at the 

 points of union ; the lower ones are somewhat pyriform, the upper lanceolate. The 

 masses of fructification are very dense, appearing to the naked eye like black grains 

 among the ramelli. When examined, by squeezing between two glasses on the table of 

 the microscope, they are seen to consist of exceedingly densely packed, minute, dichoto- 

 mous ramelli, radiating from a common centre. These ramelli scarcely differ in 

 structure from those of the ordinary whorls, and can scarcely be regarded as composed 

 of true spores ; but seem to be rather of the nature of gemmae. The general colour of 

 this species varies much : commonly it is a dark slate colour, sometimes it is olive-green, 

 and often becomes purple after having been dried. 



B. moniliforme is found in most parts of the world. It is very common in fresh- 

 water streams in Europe ; and we have received it from Van Diemen's Land, New 

 Zealand, and Cape Horn. 



II. TUOMEYA. Harv. (Nov. Gen.) 



Frond cartilaginous, continuous, solid, at first transversely banded, afterwards 

 annularly constricted ; composed of a longitudinal axis, and two strata of peripheric 

 cells. Axis columnar, consisting of several longitudinal, cohering filaments, beset with 

 closely placed whorls of moniliform ramelli, whose branches anastomose horizontally 

 and vertically into a cellular peripheric membrane, which is coated externally with 

 moniliform filaments, gradually developed. Fructification (probably in the superficial 

 filaments.) In fresh water. 



TuoMEYA fluviatiUs, Harv. 



