1110 CoDJugatse, Desmidiacefe, Micrasterias. 



Sectio i. Tetrachastrum (Dixon) Hansg. Prodr, p. 207: Semicelluhio trilobie, 

 lobis uon radiantibus. Sinus medianus cellulse et constrictiones semicellu- 

 iarum extrorsum conspicue ampliatae. Lobi mediani ampliati, couvexi vel 

 applanati, a lobis lateralibus bene discreti. 



1. Micrasterias incisa (Breb.) Kuetz. Species p. 171, Rabenh. FI. 2672 

 Eur. Alg. III, p. 188, Hansg. Prodr. p. 207, n. 435, Euasirum inei- 

 sum Breb. in Menegh. Sjn. Desm. 1840, p. 216, Euasirum bifidum 

 Focke Phjs. Stud. I, p. 45, t. I, 12 et t. II, 22 {semic. vacuat.), 

 Teirachastrum amerieanum Archer in Pritch. Inf. p. 725? — 

 Mediocris, aeque longa ac hita, 56-58 f/. diam. subpinnatisecta, 

 sinu acuto, extrorsum valde ampliato; semicellulis profunde tri- 

 lobis, lobis basalibus e basi lata in apicem trifidum sensim atte- 

 nuatis, lobo polari valde dilatato, dorso plane truncato, angulis 

 lateralibus bifidis. 



Ilah. in paludibus turfosis pr. Bremam, Berolinum (Ehren- 

 berg), ad (( Salen » badense (Jack), pr. Dresdam Germanise (L. Ra- 

 beniiorst), ad (( Franzensbad » (Hansgirg), ad (( Schluckenau » 

 in Bohemia (Karl), ad (( Aboe )) Fennise (Elfving), ad (( Gothen- 

 burgum » Sueciai (L. Rabenhorst), nec non alibi, fortasse per 

 totam Europam. — Var. excisa Nordst. in Warming Symb. ad 

 Fl. Brasil. t. 11, f. 12, Hedwigia 1870, p. 183: angulo superiore 

 loborum basalium incisura obtusangula bidentato, angulis lateralibus 

 lobi polaris vel acuminatis vel truncato-bidentatis; semicellulis a 

 vertice visis elliptico-fusiforraibus, marginibus lateralibus levissime 

 triundatis, utroque polo acuminatis; membrana subtiliter puncta- 

 ta. Ad « Lagoa Santa » in Brasilia AmericcC australis (Warming). 

 — Dimens. 32=^44, crass. 16,5 p. 



2. Micrasterias oscitans Ralfs Brit. Desmid. p. 76, t. X, f. 2, Bailey 2673 

 in Smithson. Contrib. to Knowl. 1850, t. 1, f. 19, Breb. Liste p. 121, 

 Rabenh. FI. Eur. Alg. III, p. 189, Alg. Sachs. sub n. 1853, Wolle 

 Desm. U. S. p. 116, t. 33, f. 3-4, Cooke Brit. Desm. p. 54, t. 20, 



f. 2, Hansg. Prodr. p. 208, n. 436, Holoeysiis oseiians llass. 

 Freshw. Alg. p. 387, t. XC, f. 4, Euasirum Holocysiis Kuetz. Sp. 

 p. 173, Teiraehastrum oscitans Dixon in Micr. Journal (1859) 

 1860, p. 7, Archer in Pritch. Inf. p. 725, t. II, f. 28-29. — Magna, 

 pajne tam longa quam lata, 118^98, subpinnatisecta, a vertice el- 

 liptico-fusiformis, utroque polo bifida; lobis basalibus horizontali- 

 bus conico-productis, apice bifidis; lobo polari a lobis basalibus 

 sinu amplo ac rotuudato discreto, plus minus convexo, haud raro 



