Bacillariese, Naviculacese, Frustulia. 277 



Tasson. Bacill. 1890, pag. 897, non sensu Rabenhorstii *), Van- 

 heurckia Breb. [1868] Ess. monog. sur les Vanheurckia pag. 1, 

 teste etiara Cleve in litteris 1890. — Frustula naviculacea, libera 

 vel rarissime in serie simplici in tubo membranaceo-mucoso nidu- 

 lantia ; valvte ssepius lanceolatse, striis subtilissimis, parallelis, trans- 

 versis, in medio valvae paullulo radiantibus donatae; nodulus cen- 

 tralis et noduli terminales inter 2 ramos rhaphes duplicis siti. 



I. Eu-Frustulia: Eu-Vanheurckia V. H. Syn. p. 112. 

 Strise omnes parallelae. 



1. Frustulia rhomboides (Ehr.) De-Toni, Navicula rhomboides Ehr. 1159 

 Verbr. t. 3, I, f. 15, Kuetz. Bacill. p. 94, t. 28, f. 45, t. 30, f. 44, 

 W. Sm. Br. Diat. I, p. 46, t. 16, f. 129, Rabenh. Fl. Eur. Algar. 

 I, p. 171, Vanheurckia rhomboides Breb. Ess. Monogr. Vanh. 

 p. 4, n. 3, V. H. Syn. p. 112, t. 17, f. 1-2, Truan Diat. Astur. 

 p. 46, t. 2, f. 1. — Valvis rhomboideo-lanceolatis, 70-80 \x. longis, 

 apices versus attenuatis leniterque constrictis; rhaphe duplici e 

 filis 2 approxiraatis continuis efformata, nodulis terminalibus ob- 

 longo-linearibus, endochromate flavescente; striis transversis sub- 

 tilibus, rhaphen attingentibus, circiter 20 in 10 \j.., subtiliter gra- 

 nulatis. 



Hab. in fontibus, aquariis, fossis aquse dulcis passim, imprimis 

 ad «Falaise GalliaB» inventa (Brebisson) ; in Austria, Germania, An- 

 glia, Belgio, Tyrolia, Hungaria, Hispania; etiam in Mexico (teste 

 Ehrenberg). — Var. amphipleuroides Grun. in Cl. et Gr. Arct. 

 Diat. p. 47, t. 3, f. 59. — Major; valvis 21 p. latis; striis trans- 

 versis 23 in 10 \x. ; striis longitudinalibus paullulo undulatis, 18- 

 19 in 10 [x., nodulo centrali valde elongato. In «Jenissey» (Gru- 

 now). — Var. saxonica (Rab.), Navicula crassinervia Breb. in W. 

 Sm. Br. Diat. I, (1853!), pag. 47, t. 31, f .27 1 , Fruslulia saxonica 

 Rabenh. Bacill. exs. (1851!) p. 42, Fl. Eur. Algar. I, p. 227, incl. 

 fig. b et c, Frusiulia lurfacea A. Br. in Rabenh. Siissw. Diat. 

 p. 50, t. 7, f. 2, Alg. n. 761, Vanheurckia crassinervia Breb. 

 Ess. Monogr. Vanh. p. 4, n. 4, Truan Diat. Astur. pag. 46, t. 2, 

 fig. 2, Vanheurckia rhomboides var. crassinervia V. H. Syn. 



*) Mirum quod cl. Rabenhorst, contra Grunow, characterem peculiarem 

 Frustulm ab ipso emendatae indicat nodulorum et centralis ct terminalium 

 absentiam; attamen in genere Frustulia disposuit species distincte nodulife- 

 ras, e. gr. Frustuliam trigrammam (Fresenius). 



