174 v. T. CLEVE, SYNOPSIS OF NAVICUr.OII) IM ATOMS. 



around the central nodule. StriiB 14 to 15 in 0,oi mm. radiate in the middlp, almost parallfd at 

 ends, very finely pimctate, crossed oii the venti-al side below the central nodule by a narrow de- 

 pression. — Coccon. Stuxh. Cl. A. D. p. 13 Pl. I f. 10. önmh. St. Icon. n. Pl. V f. 2. 

 Frcsh water: Mouth of Jenissey! 



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

 ventral margin straight, somewhat gibbous in the niiddle. L. O, i9 to 0,2 5; B. 0,o.3 2 mm. Median 

 line slightly arcnate, dilated towards the ends; its terminal fissnres reflexed. Axial area narrow 

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

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

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

 Ung. p. 140 Pl. XXX f. 35. Pant. III 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 G. lanceolata, and the row of pnncta of C. Ci-stula. 



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

 cave, centrally gibbous, ventral margin, and obtuse ends. L. O, os to O, le; B. 0,o24 to O.os mm. 

 Median line sliglitly arcuate with reflexed terminal fissures. Axial area verj- narrow; central 

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

 mm. — Coccon. lanceolatum Ehb. Inf. p. 224 Pl. Xix'f. 6. W. Sm. B. I). I Pl. XXIII f. 219. 

 A. S. Atl. X f. 8—10. Cijmb. lanc. V. H. Syn. p. 63 Pl. II f. 7. Coccon. Boeclcii Grun. in A. S. 

 Atl. X f. 11 (1875). Coccon. variaUle Cramer, Rab. A. E. 1246 (p. p. C. cymbifera). 



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

 Skåne)! Gulf of Bothnia! Norway (Finmark to Laurgård)! Finland (Ladoga, Onega)! Siberia! Hol- 

 stein! Britain! France! Belginm (V. H.), Switzerland! Yienna! Socotra (Kitton). 



Var cornuta Ehb. (1843). — L. 0,i5 to 0, 20; B. 0,027 to 0,029 mm. StriiE 7 or 8 (middle) 

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

 Am. p. 124. M. G. XV, Ä f. 94. Cymh. lanc. var. cornuta Grun. Foss. D. Österr. Ung. p. 141. 



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



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

 mm. — Pant. II p. 40. 



Brackish water: Hnngary, fossil (Pant.). 



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

 straight, frequently slightly gibbous ventral. Ends rounded obtuse. L. 0,036 to 0,os5; B. 0,ui to 

 0,015 mm. Median line slightly asymmetrical and almost straight. Terminal fissnres in nearh- 

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

 nodule. Strise 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. — KiJTZ. Bac. p. 79 Pl. VI f. 13. V. H. Sjai. 

 p. 64 Pl. II f. 15. A. S. Atl. X f. 20 to 21, 22 {Cymh. scotica) f. 23 {Coccon. lare); LXXI f. 19. 



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

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

 Switzerland! 



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

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

 in Cl. M. D. N:o 95. 



Fresh water: Holstein! 



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

 L. 0,0 9; B. 0,0 2 6 mm. Striai about 8 in 0,oi mm. — Cymh. Bal. Grun. A. S. Atl. X f. 19. 



Fresh vv^ater: Plätten See, Hungary (Grun.). 



