feaciilarieae, Naviculaceas, Navicula. 57 



139. Navicula dicephala Ehr. Inf. 1838, p. 185, Kuetz. Bacill p 96 139 



t. 28, f. 60 et 62, W. Sm. Br. Diat. I, p. I, p. 53, t. 17, f. 157, 



Grun. in Wien. Verhandl. 1860, p. 538, t. 2, f. 45, Cl. et Gr. Arct. 



Diat. p. 34, A. Schm. Atlas t. 44, f. 33-34, t. 72, f. 29-33, V. 



H. Syn. p. 87, t. 8, fig. 33-34, Bull. Torr. B. Cl. 1887, pag.Wl, 



t. m, f. 8 (non Pinnularia biceps Ehr.), Navicula undula Schum. 



Preuss. Diat. 1863, p. 188, f. 37, Rabenh. Fl. Eur. Algar. I, p. 209? 



Pinnularia dicephala Ehr. Iofus. p. 185, Amer. t. 2, I, f. 29, II, 



f. 15, M. t. 6, I, f. 10 a, t. 5, I, f. 19, t. 17, I, f. 11, XV, f.V-9 



etc, Rabenh. S. D. p. 44, t. 6, f. 44, Schum. P. D. 1862, p. 9, f. 27. — 



Valvis angustis, linearibus, 23-40 * 10-12, apicibus constrictis, ob- 



tuso-capitato-rostratis; striis transversis circa nodulum medianum 



magnum et rotundato-quadrangularem valde abbreviatis, usque ad 



apices valvae radiantibus, granulatis, circiter 9-11 in 10 a. 



Hab. in aquis dulcibus passim in Anglia, Gallia, Helvetia, Ger- 

 mania, Austria inferiori, Galicia, Rossia, Serbia; in America boreali 

 et australi (Ehrenberg) ; fossilis in Italia, Suecia et Islandia. — 

 A Navicula Placentula var. anglica differt forma valvarum li- 

 neari, a Navicula infiala eadem ratione. 



140. Navicula elginensis (Greg.) Ralfs in Pritch. Inf. p. 902, Cl. et 140 

 Gr. Arct. Diat. p. 35, Pinnularia elginensis Greg. in Micr. Journ. 

 1856, t. 33, f. 33. — Naviculm dicephalcc simillima (nisi eadem?); 

 valvis 25-35 « 9-10,5; striis pr. apices non radiantibus sed eximie 

 transversis; rhaphe area hyalina, late levi cincta; striis transver- 



sis 12-14 in 10 u. 



Hab. in Scotia (Gregory, Grunow). 



141. Navicula lanceolata Kuetz. Bacill. pag. 94, t. 30, f. 48!, t, 28, 141 

 f. 38, Rabenh. Siissw. Diat. pag. 39, t. 6, f. 77, Fl. Eur. Alg. I, 



p. 175, Grun. in Wien. Verh. 1860, nag. 527, t. 2, f. 26, Schum. 

 1862, t. 9, f. 38, Weisse 1860, t. 1, f. 35, A. Schm. Atlas t. 47, 

 f. 49, Cl. et Gr. Arct. Diat. p. 35, Lagerst. 1884, p. 50, f. 5, V. 

 H. Syn. p, 88, t. 8, f. 16-17, Frustalia lanceolata Kuetz. Syn. 

 pag. 14, t. 1, fig. 13, Navicula gracilis W. Sm. Brit. Diatom. I, 

 t. 18, f. 174?, non Ehrenberg! — Valvis lanceolatis, 30-50 » 9-1 1, 

 apicibus plus minus sed leniter attenuato-rostratis; striis transver- 

 sis circa nodulum medianum abbreviatis et aream hyalinam rotun- 

 datam circa eum linquentibus, usque fere ad apices valva3 radian- 

 tibus, subtiliter punctatis, in valvao medio 12, ad apices 15-16 in 

 10 u., facie connectivali lineari, ad utrumque finem parum atte- 

 nuata, apicibus truncatis. 



