182 p. T. CLEVE, SYNOPSIS OF THE NAVICULOID UIATOMS. 



Var. dichototna KtJTZ (1833). — L. 0,04 to 0,o6; B. O.oos mm. Striae 11 to 13 in 0,oi mm. 

 — G. dichot. KtJTz. Syn. D. p. 569 f. 48. Bacil. p. 85 PI. VIII f. 14. W. Sm. B. D. PI. XXIX 

 f. 241? G. intr. var. dich. V. H. Syn. p. 125 PI. XXIV f. 30—31. G. pulvinatum Al. Br. in E,ab. 

 Slissw. D. p. 58 (1853). V. H. Syn. f. 32 to 34. 



Fresh water: Finland! Zurich! Australia (Victoria, Lake Muir, Tasmania)! 



Var. fossilis Pant. (1889). — L. 0,045; B. 0,oo75 mm. Striae 10 to 12,5 in 0,oi mm., the 

 median more distant, 7,5 in 0,oi mm. — Pant. II p. 56 PI. XI f. 201. 



Brackish water: Hungary, foss. (Pant.). 



Var. Vibrio Ehb. (1843). — V. very slender and narrow, linear, slightly gibbous in the 

 middle, with rounded-truncate often gibbous ends. L. 0,08 to O,oii; B. 0,oi to 0,oi2 mm. Striae 

 10 in 0,01 mm. distinctly punctate. — G. Vibrio Ehb. Verb. p. 128 PL II: 1 f. 40. Microg. "W. Sm. 

 B. D. PL XXVIII f. 242. V. H. Syn. PL XXIV f. 26—27. G. Cygnus Schum. P. D. p. 187 

 PL IX f. 26? 



Fresh water: Finland! Germany, Erlaf See (Grun.), Hungary, Dubravica, fossil (Grun.), 

 Seychelles ! 



To this species probably belongs G. hungaricum Pant. Ill PL II f. 28 (1893). 



5. G. subtile Ehb. (1843). — V. narrow, elongate,d biconstricted, with broad, rounded- 

 truncate apex. L. 0,045; B. 0,oo7 mm. Axial area indistinct; central area narrow, unilateral, 

 transverse. Striae 12 in 0,oi mm., almost transverse, distinctly punctate. — Ehr. Am. p. 128. 

 Greg. M. J. IV PL I f. 12. Schum. P. D. I Nacht. PL II f. 19. V. H. Syn. PI. XXIII f. 13, 14. 



Fresh water: Scotland! Finland! Holstein! Bengal! 



Var. Sagitta Schum. (1863). — As the type, but with cuneate apex. — G. Sagitta Schum. 

 P. D. p. 187 PL IX f. 29. V. H. Syn. PL XXIII f. 27. 

 Fresh water: Prussia (Schum.). 



6. G. semiapertum Grun. (1880). — V. elongated, clavate, with broad apex and basis. L. 

 0,06 to 0,07; B. 0,011 to 0,013 mm. Axial area distinct, linear; central area a large, transverse 

 fascia, with a distinct stigma on one side and frequently marginal striae on the other. Striae 10 

 to 11 in 0,01 mm., slightly radiate, punctate; puncta about 21 in 0,oi mm. — Grun. in V. H. Syn. 

 PL XXIV f. 42. Cl. M. D. N:o 264. 



Fresh water: California, Shasta Co (Grun.), Oregon, Pitt River (Grove Coll.)! 



7. G. gracile Ehb. (1838). — V. elongated, linear to lanceolate, with acute to s^^bacute apex 

 and basis. L. 0,025 to 0,07; B. 0,04 to O.oiii mm. Axial area very narrow; central area narrow, 

 transverse. Striae transverse, 9 to 15 in 0,oi mm. 



Var. cymbelloides Grun. Ms. — V. slightly asymmetrical to the longitudinal axis, with gently 

 curved dorsal margin and nearly straight ventral margin. L. 0,03; B. 0,oo5 mm. Striae about 

 16 in 0,01 mm. 



Fresh water: Norway, Dovre! Sweden, Helsingland, Arbra! 



Var. aurita Al. Br. (1853). — V. narrow, linear-lanceolate. L. 0,024 to 0,04; B. 0,oo5 to 

 0,006 mm. Striae 15 to 16 in 0,oi mm. Living cells with two horn-like processes at the end. — 

 G. aur. Al. Br. in Rabh. Stissw. D. p. 59 PL VIII f. 3. V. H. Syn. XXIV f. 15 to 18. G. an- 

 gustum Schum. I Nachtr. PL II f. 17? 



Fresh water: Baden, Titisee (A. Br.), Finland! Norway, Dovre! Iceland! U. St. Bemis Lake, 

 White Mountains! 



Var. dichotomum W. Sm. (1853). — Linear-lanceolate, slightly clavate, with obtuse ends. 

 L. 0,04 to 0,05; B. 0,007 mm. Striae 12 to 14 in 0,oi mm. finely punctate. — G. dichotomum 

 W. Sm. Br. D. I p. 79 PL XXVIII f. 240. G. {gracile var.?) dichotomum V. H. Syn. PL XXXV 

 f. 19 to 21. G. tenellum W. Sm. B. D. PL XXIX f. 243? G. Vibrio Schum. Tatra PL III f. 38? 

 G. hebridense H^rib. D. d'Auvergne p.' 61 PL III f. 9? 



