Conjugatae, Desmidiaceae, Xanthidiura. 917 



Alg. n. 1430 et sub n. 484, Fl. Eur. Algar. III, p. 222, Archer in 

 Pritch. Inf. p. 735, t. I, f. 27 et 28, De-Not. Element. p. 47, n. 34, 

 t. IV, f. 35, Wolle Desm. U. S. p. 92, t. 21, f. 1-4, Kirchn. Alg. 

 Schles. p. 154, Cooke Brit. Desm. p. 129, t. 45, f. 1, Hansg. Prodr. 

 p. 373, f. 114, De-Toni e Levi Fl. Alg. Ven. III, p. 52, Wittr. et 

 Nordst. Alg. aq. dulc. exsicc. n. 168, 264, 822, Cosmariutn ar- 

 matum Breb. mscr. 1839 et in Menegh. Synops. in Linn. 1840, p. 

 Z\%Zygoxanthium Echinus Ehrenb in Berl. Monatsb. 1840, Kuetz. 

 Spec. p. 178 Xanthidium Echinus Ehrenb. Berl. Naturf. Gesellsch. 

 18, Juni 1839, Xanthidium furcatum Ralfs in Ann. and Mag. of 

 Nat. Hist. 1844, p. 466, t. XII, f. 1 excl. syn., Euastrum armatum 

 Kuetz. Phycol. germ. p. 137. — Maximum, validum, solitarium vel 

 binatira conjunctum, diametro plerumque duplo longius, 120-200=; 

 62-140, sinu extrorsura ampliato; semicellulis subcordatis vel an- 

 gulari-rotundatis, tubercuio centrali subelevato, truncato, raargine 

 granulato-dentato praeditis ; chlorophoris 4, parietalibus, pyrenoides 

 plures obvolventibus; membrana verruculosa et processibus sa^pius 

 geminatis, truncatis, apice inciso-furcatis instructa; zygotis 100-108 

 (j. diam. aculeatis. 



Hab. in fossis stagnisque turfosis imprimis in Italia (De-Nota.- 

 RIS, De-Toni, Levi), Gallia (Brebisson, Petit), tota Britannia (Ar- 

 CHER, Ralfs, Cooke, Hassall), Germania (Kirchner, Rabenhorst, 

 Kuetzing), Bohemia (Hansgirg), Suecia (Cleve, Lundell), Norve- 

 gia (Nordstedt), Dania (Jacobsen), Hungaria (Istvanffi), Belgio 

 (De-Wildeman), Fennia (Elfving), America boreali (Wolle, La- 

 gerheim), ins. Cuba (Lagerheim), Birmania (Joshua). — Var. ame- 

 ricanum Turner in Journ. Royal Micr. Soc. 1885 Decemb. ser. II, 

 vol. V, p. 938, t. XV, f. 19: scrobiculis bene definitis. Dim. (spin. 

 excl.) 70-123 iJ 38-73; lat. isthmi 31-37 'j.. In America boreali. 

 — Var. Wolleanum Turner 1. c. t. XV, f. 18: magnum, dimensiones 

 formae typica^ valde excedens, punctulatum. Dim. (spin. excl.) 168 

 a 104, lat. isthmi 42 p.. In Araerica boreali. — Var. basidenta- 

 tum Nordst. Freshw. Alg. of N. Zeal. and Austral. p. 42, t. 4, f. 21, 

 Botaniska Notiser 1877, p. 158, et Notarisia 1888, p. 411: angulis 

 inferioribus semicellularum dente vel verruca parva ornatis ; pro- 

 cessibus vulgo bifidis, rare indivisis vel trifidis; merabrana punctato- 

 scrobiculata, ut in forma typica. Long. cura proc. c. 120 u., lat. 

 100 ij.., crass. 64-67 (j.. Ad «Taupo» «Omatangi», «Tongariro-Rua- 

 pehu» in Nova Zelandia (S. Berggren). — Var. fissum Nordst. 

 De Algis et Characeis Sandwicensibus p. 17, t. II, f. 6: semicel- 



