180 BRITISH CHAROPHTTA. 



diverges in the direction of the GharesB. The mem- 

 brane of the oospore has usually no outgrowth in the 

 shape of crest or basal appendages. The fruiting 

 whorls usually form dense heads, and the divergent 

 often incurved rays of the branchlets cause them to 

 assume a characteristic bird's-nest-like appearance, 

 which suggested the specific name nidifica, given to 

 the first species recognized. 



The stem and branchlets are often densely incrusted, 

 but the incrustation is not in rings as in Nitella. In 

 some species a lime-shell is secreted in the spiral-cells 

 of the oogonium. 



Dr. T. F. Allen gave considerable attention to this 

 genus, and his ' Notes on the American Species of 

 Tolypella' in Bull. Torrey Bot. Club, X, pp. 109-117, 

 tt. 37-42 (1883) will be found useful to students of the 

 British plants. 



The known species of Tolypella number about four- 

 teen, all of which occur in the northern and only few 

 in the southern hemisphere. 



Section 1 . CONOIDE^l (= Acutifolia ALLEN). 



Ultimate cell of rays short, more or less conical and 

 acute. Spiral-cells of oogonium not swelling at the 

 apex. Coronula persistent. 



1. Tolypella intricata Leonhardi. 

 (PLATE XVII.) 



Chara intricata ROTH Catal. bot. II, p. 125 (1800). 



Nitella intricata AGAEDH Syst. Alg. p. 125 (1824). 

 NOEDSTEDT in Bot. Notiser, 1863, p. 39. 

 CEEPIN in Bull. Bot. Soc. Belg. II, p. 130 (1863). 

 LANGE in Flora Danica, t. 2744 (1867). 

 BEAUN in Monatsb. Akad. Berl. for 1867, p. 895 (1868). 

 MULLEE in Bull. Soc. Bot. Genev. II, p. 56 (1881). 

 COSSON & GERMAIN Atl. Fl. Par. ed. 2, t. 47, f . I (1882). 

 BOSWELL Engl. Bot. ed. 3, XII, p. 187, 1. 1907 (1884). 



C. fasciculata AMICI in Mem. Accad. Sc. Modena, I, p. 212, t. 4, f. 4, t. 5, 

 f. 3 (1827). 



