174 p. T. CLEVE, SYNOPSIS OF NAVICULOID DIATOMS. 



around the central nodule. Strife 14 to 15 in 0,oi mm. radiate in the middle, almost parallel at 

 ends, very finely punctate, crossed on the ventral side below the central nodule by a narrow de- 

 pression. — Goccon. Stuxb. Cl. A. D. p. 13 PL I f. 10. Cymb. St. Icon. n. PI. V f. 2. 

 Fresh water: Mouth of Jenissey! 



56. C. Sturii Grun. (1882). — V. boat-shaped, with truncate ends. Dorsal margin arcuate, 

 ventral margin straight, somewhat gibbous in the middle. L. 0,i9 to 0,25; B. 0,o32 mm. Median 

 line slightly arcuate, dilated towards the ends; its terminal fissures reflexed. Axial area narrow 

 linear, gradually dilated towards the middle and the ends. Strife 7 or 8 (middle) to 10 or 12 

 (ends) in 0,oi mm. punctate (puncta about 14 in 0,oi mm.), crossed near the central nodule on the 

 ventral side, and sometimes on the dorsal side, by a narrow depression. — Gkun. Foss. D. Osterr. 

 Ung. p. 140 PL XXX f. 35. Pant. Ill PL XIX f. 287. 



Fresh water: Hungary, fossil! 



This species is very characteristic, distinguished from all others by its median line becoming 

 wider towards the ends. It has the outline of C. lanceolata, and .the row of puncta of C. Cistula. 



57! C. lanceolata Ehb. (1838). — V. boat-shaped, with arcuate dorsal margin, slightly con- 

 cave, centrally gibbous, ventral margin, and obtuse ends. L. 0,o8 to 0,i6; B. 0,024 to 0,o3 mm. 

 Median line slightly arcuate with reflexed terminal fissures. Axial area very narrow; central 

 area small, elongated. Striae 9 to 10 in 0,oi mm. slightly radiate, punctate, punota 15 to 18 in 0,oi 

 mm. — Goccon. lanceolatum Ehb. Inf. p. 224 PL XIX f. 6. W. Sm. B. D. I PL XXIII f. 219. 

 A. S. Atl. X f. 8—10. Cymb. lane. V. H. Syn. p. 63 PL II f. 7. Goccon. Boechii Grun. in A. S. 

 Atl. X f. 11 (1875). Goccon. variabile Ceamer, Rab. A. E. 1246 (p. p. C. cymbifera). 



Fresh water, especially larger lakes, often slightly brackish water: Sweden (Lapland to 

 Skane)! Grulf of Bothnia! Norway (Finmark to Laurgard)! Finland (Ladoga, Onega)! Siberia! Hol- 

 stein! Britain! France! Belgium (V. H.), Switzerland! Vienna! Socotra (Kitton). 



Var cornuta Ehb. (1843). — L. 0,i5 to 0,2o; B. 0,o27 to 0,029 mm. Striee 7 or 8 (middle) 

 to 10 or 11 (ends) in 0,oi mm. punctate; puncta 10 to 12 in 0,oi mm. — Goccon. cornutum Ehb. 

 Am. p. 124. M. Gr. XV, A f. 94. Gymb. lane. var. cornuta Grun. Foss. D. Osterr. Ung. p. 141. 



Fresh water: Ireland, Toome Bridge, Mourne Mountains (Grun.), Ltineburg (Grun.). 



Var. fossilis Pant. (1889). — L. 0,127; B. 0,024 mm. Striee 11 (middle) to 8 (ends) in 0,oi 

 mm. — Pant. II p. 40. 



Brackish water: Hungary, fossil (Pant.). 



58. C. helvetica Kutz. (1844). — V. boat-shaped, with gently arcuate dorsal margin and 

 straight, frequently slightly gibbous ventral. Ends rounded obtuse. L. 0,036 to 0,085; B. 0,oi to 

 0,015 mm. Median line slightly asymmetrical and almost straight. Terminal fissures in nearly 

 the same direction as the median line. Axial area narrow, very slightly dilated around the central 

 nodule. Striee 9 to 11 in 0,oi mm. closer towards the ends; puncta about 16 in 0,oi mm. There 

 are no isolated puncta below the central nodule. — KtJTZ. Bac. p. 79 PL VI f. 13. V. H. Syn. 

 p. 64 PL II f. 15. A. S. Atl. X f. 20 to 21, 22 {Gymb. scotica) f. 23 {Goccon. Iceve); LXXI f. 19. 



Fresh water: Greenland! Norway (Finmark, Stavanger, foss.)! Sweden (Lapland to Skane)! 

 Gulf of Bothnia (Haparanda, Pitea), Finland! Scotland! Belgium (V. H.), Germany! France! 

 Switzerland! 



Var. curta Cl. — L. 0,045; B. 0,012 mm. Central area smaller than in the type, or in- 

 distinct. Striae 12 in 0,oi mm. less distinctly punctate than in the type. — G. turgidula Grun. 

 in CL M. D. N:o 95. 



Fresh water: Holstein! 



Var.? Balatonis Grun. (1875). — Dorsal margin strongly arcuate, ventral slightly gibbous. 

 L. 0,09; B. 0,026 mm. Striae about 8 in 0,oi mm. — Gymb. Bal. Grun. A. S. Atl. X f. 19. 



Fresh water: Flatten See, Hungary (Grun.). 



