CHARACE.E, 185 



Monoecious. Dark green. Stems capillary, pellucid, without 

 cortical cells or spine-cells or stipule-cells. Branclilets 5 to 8 in a 

 whorl, most of them 3 to 7 times bi- or tri-furcate, the ultimate 

 divisions longer than the lower, 2-celled and longly mucronate, those 

 of all the whorls very compact with short segments, so that the whorls 

 resemble widely separated heads which are mucilaginous and generally 

 encrusted. Nucules solitary immediately below all the forks of the 

 rays of the branches, ovoid, 7- to 9-striate with a very minute 

 deciduous crown. Globules solitary between the forks of the 

 branchlets immediately above the nucules. 



In fen ditches and pits, very rare. In Roydon Fen, Norfolk ; 

 Bottisham, Wicken, and Burwell Fens, Cambridgeshire ; Anglesea, 

 (J. E. Griffith) ; first found by Professor Henslow in 1829. 



England, Wales. Annual. Summer, Autumn. 



A very elegant species, usually 2 to 3 inches high, primary branches 

 -j^ to -^ inch long, whorls usually \ to ^ inch apart, but sometimes less. 



I have a fine series of specimens of this, collected in Burwell Fen by 

 Dr. J. A. Power, and one from Bottisham Fen collected by Mr. C. A. 

 Stevens in May, 1838. 



N. tenuissima comes near to N. gracilis, but is much smaller, 

 and very different in appearance from the extreme shortness of the 

 branches, though it is difficult to find any marked distinction between 

 them. The terminal or mucro cell of the ultimate rays of the branch- 

 let is longer in proportion and more gradually tapering than in N. 

 gracilis. 



Dwarf Nitella. 



Section II.— TOLYPELLA. A. Braun. 



Globules on the inner side of and at the first node of branchlets, 

 accompanied by 2 to 4 bracts, similar to the branchlet but shorter 

 and generally unequal. Nucules surrounding the globule. 



SPECIES VII.— N ITELLA GLOMERATA. CkevaUier. 



Plates 1905 and 1906. 



Monoecious (or rarely dioecious ?). Pale or dark olive. Stem rather 

 stout, transparent or much more commonly opaque from being thickly 

 encrusted with carbonate of lime, without cortical cells or spine-cells 

 or stipule-cells. Branchlets 6 to 12 in a whorl, those of the primary 



VOL. xii. 2 b 



