CoDjugatae, Desmidiacese, Pleurotsenium. 905 



BORSKi), Birmania (Joshua), Araerica boreali (WooD, Wolle). — 

 Specimina ex Lituania, teste Raciborski, cellulas 60-74 s 6-7 prse- 

 bent. — Var. gracile Wille Bidrag Norg. Ferskvandsalger p. 51, 

 t. II, f. 33: gracillinium, IH'*^, basi semicellularura non turaida. 

 Ad « Haabol » Norvegise (Wille). — Var. tumidum Wille 1. c. 

 p. 51, t, II, f. 34: fere 5-plo longius quam latum, 70^ 15; isthrao 

 11 p.. lato; seraicellulis tumidis. Ad « Haabol » Norvegiae (WiLLE). 



Tribus quarta Micrasteriese (Endl.) 



Micrasterice Endl. [1836] Gen. p. 3 ex parte, Trevis. [1842] Prosp. fl. Eug. p. 58 

 ex parte {Eumicrasteriece) em. De-Toni [1888] Consp. gen. Chloroph. in No- 

 tarisia III, n. 10, p. 452. 



Desmidieai incisce Kirchn. [1878] Alg. Schles. p. 145. 



Didymiacece incisce Hansg. [1888] Prodr. p. i90. 



Cellulas constrictione profunda in partes 2 symraetricas (semicel- 

 lulas) distinctae, e vertice visse tantum raro orbiculares, plerumque 

 ovales, ellipticse, 3-4-goni0e, soepe tuberculis instructae. 



A. Chlorophora parietalia (laminc-eformia) 

 Pleuroto&niopsis. Cellulse breviter cyliudraceas vel rotundatcB, medio plus mi- 



nus profuude incisEe, apicibus rotuudatse vel truncatae. 

 Xanthidium. Cellulre ut in Pleurotceniopsicle medio constrictffl, ambitu orbi- 



culares, oblongas vel multangulata), vertice tum emurginatse, tum incisse, 



superflcie aculeis vel prominentiis (apice flssis) 16 instructae, e vertice ro- 



tundat» vel oblongte. 



B. Chlorophora axilia seu centralia. 



Cosmarium i). Cellulfe breviter cylindraceas vel orbiculares , margine saepe 

 crenatse, undulatte vel excavatae, apicibus rotuudatae vel applanatae, nec 

 incisae, e vertice ovales, compressse vel ellipticae, quandoque utrinque 

 tumidse; chlorophora in utraque seraicellula 1-2, dlscreta, radiata, pyre- 

 noide singulo centrali vel duobus symmetrice dispositis. 



j4rthrodesmus. Gelliike ut in Co5?«ariO ; semicellulae utrinque aculeis subula- 

 tis 4-8 instructas, e vertice visse oblongse vel ellipticse, utrinque non tu- 

 midae; chlorophora tteniaeformia. 



Euastrum. Cellulse ambitu oblong» vel ellipticae, medio profunde constrictae, 

 lateribus plerunque symmetrice excavatte vel laciniatae, apicibus rotunda- 

 tse vel truncatfe ideoque suberaarginatfe vel incisura angusta bifidae, e 

 vertice visse oblongce et in utroque latere tuberculis l-pluribus hemisphae- 

 ricis instructse; chlorophora pyrenoide singulo (rarius duobus) prsedita. 



1) Genus novum proposuit, ob chlorophororum formam, clarus Strockmayer 

 sub nomine Astrooosmii Cfr. Strockmayer Uebor eine neue Desmidiaceen. — 

 GattuDg in Verhandl. K. K. Zool. bot. Gesellsch. in Wien XXXVIII, 4, 1888 

 p. 85. 



