1134 Conjugata3, Desmidiacei-e, Micrasterias. 



52. Micrasterias Thomasiana Archer in Micr. Journ. 1862, p. 239, ^723 

 t. XII, f. 1-10, Rabenh. Fl. Eur. Algar. III, p. 192, Cooke Brit. 

 Desra. p. 58, t. 25, f. 1, Micrasterias deniiculata v. Thomasiana 

 Jacobs. Apergu p. 187. — Permagna, orbicularis, pauUo longior 

 quam latior, 200^177, levis; semicellulis basi tumoribus tribus in 

 seriem simplicem dispositis, lateralibus elongatis uncinato-recur- 

 vatis, intermedio conice rotundato instructis, quinquelobis; lobis 

 omnibus confertis, basalibus et intermediis profunde bilobulatis; 

 lobulis incisura levi in duo segmenta fequilata partitis; segmentis 

 ipsis etiam bipartitis, lacinulis bidentatis; lobo polari non promi- 

 nente, subanguste cuneato, vertice excisura angusta acutangula, 

 angulis acutis, vix denticulatis ; cellula a vertice conspecta lan- 

 ceolata, utrinque processibus tribus prominentibus. 



Hab. in lacubus Hiberniae prope « Old Gable n (Archer), in 

 massa quadam inter Diatomeas varias ad a Prenzlau » Borus- 

 sise (Rabenhorst), in Suecia (Lundell), Norvegia (Nordstedt), 

 Dania (Jacobsen), Fennia (Elfving), Polonia (Raciborski). — Ex 

 ipso Rabenhorst species insignis .1/. furcaicB proxima sed ab illa 

 et ab omnjbus affinibus differt tumoribus ad semicellularum basin. 



53. IVIicrasterias americana (Ehrenb.) Kuetz. Species p. 171, Ralfs 

 Brit. Desm. p. XIX. Breb. Liste p. 121, Rabenh. FI. Eur. Alg. III, 

 p. 189, Kirchn. Alg. Schles. p. 161, Wolle Desm. U. S. p. 112, 

 t. 32, f. 2. Cooke Brit. Desm. p. 56, t. 30, f. 1, Euasirum ame- 

 7'icanum Ehrenb. Verb. p. 125, t. IV, f. 5, Micrasierias morsa 

 Ralfs Brit. Desm. p. 74, t. X, f. 1, Micrasterias Herrmanniana 

 Reinsch Algenfi. p. 141, t. VIII, f. 1 saltem ex parte. — Magna, 

 augulato-elliptica, subpinnatisecta vel triloba, lobis polaribus paul- 

 lum remotis, paene duplo longior quam latior; a latere visa oblonga, 

 in medio leviter constricta utroque polo bicornuta; membrana plus 

 minus punctata ; marginibus loborum dentato-serratis; semicelluiis 

 basi turaore plus minus distincto instructis, fere quinquelobis, lo- 

 bis basalibus latissimis iisdemque profunde bilobatis, lobulis late 

 excisis (rarissime inferioribus integris) segmentis dentato-serratis; 

 lobis polaribus plus mimo productis, in medio late excisis, seg- 

 mentis profunde bifidis. 



Hah. in stagnis turfosis in Britannia (Ralfs, Cooke), Gallia 

 (Brebisson), Germania (Rabenhorst, Kirchner), Suecia (Cleve, 

 Lundell), Norvegia (Nordstedt), Groenlandia (Boldt), America 

 boreali (Wood, Wolle). — Dimens. 100-153 ^ 92-132. — Var. recta 

 WoUe Bull. Torr. Bot. Club 1876, Desm. U. S. p. 112, t. 32, f. 3: 



