172 p. T. OLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



Fresh water: Sweden (Uppland to Skane, Grothland, Gulf of Bothnia)! Finland! Holstein! 

 England! Belgium (V. H.), Germany! Switzerland! Italy! Mouth of Jenissey! Japan! Australia 

 (Lake Muir)! New Zealand! New York! Argentina! 



Cyinh. affiiiis is a variable species, connecting Cymb. turgidula with Cymb. parva. The 

 ventral margin is sometimes indented in the middle. Such a form has been figured by Grunow in 

 Foss. Diat. Osterr. Ung. PL XXIX f. 26 and is probably identical with Cymb. exisa var. major 

 GuTwiNSKY Materialy p. 25 PL I f. 21. 



50. C. parva W. Sm. (1852). — V semilanceolate, with slightly rostrate, obtuse to sub- 

 truncate ends. L. 0,03 to 0,05; B. 0,oi to 0,oi2 mm. Median line somewhat arcuate and broad 

 (oblique). Axial area narrow, very slightly dilated in the middle. Striae 9 or 10 (median, dorsal) 

 to 13 (ventral and terminal) in 0,oi mm., very slightly radiate, obscurely punctate. There is no 

 punctum on the ventral side of the central nodule. — Cocco. parvum W. Sm. B. D. I p. 77. PL 

 XXIII f. 222. A. S. Atl. X f. 14, 15. Getjn. Franz Josephs Land D. p. 97 (45) PL I f. 9. Cijmb. cymhy- 

 formis var. parva V. H. Syn. p. 64 PL II f. 14. Cocconema pachycephalum Rabh. Alg. Eur. 

 N:o 1107 (1861). 



Fresh water: Greenland! Franz Josephs Land (Grun.), Sweden (Lapland to Skane)! Norway 

 (Finmark to Christiania) ! Finland! England! Germany! Belgium! France! Switzerland! Savoy! 

 Italy! Mouth of Jenissey! North America, Winnepeg! 



Var. hungarica Grun. (1875). — L. 0,024 to 0,04; B. 0,oo9 to 0,oi mm. Area dilated on 

 the dorsal side of the central nodtile. Strise 10 in 0,oi mm. — Coecon. hungaric. Grun. in A. S. Atl. 

 IX f. 38, X f. 16, 17; LXXI f. 37, 38. 



Fresh water: Norway (Brevig)! Platten See, Hungary (Grun.). 



Cymb. parva is in the living state stipitate. It is closely akin to Cymb. affinis and 

 Cymb. cymbiformis, diifering from both by the want of a punctum at the end of the median 

 central stria. 



51. 0. Botellus Lagst. (1873). — V. arcuate, with parallel margins and rounded ends. 

 L. 0,024 to 0,034; B. 0,006 to 0,007 mm. Median line slightly excentric, arcuate. Axial area 

 narrow, not dilated around the central nodule. Strise 10 to 11 in 0,oi mm., very slightly radiate, 

 not distinctly punctate. — Cymb. variabilis var. Botellus Lagst. Spitsb. D. p. 44 PL II f. 22. 

 Cymb. bot. A. S. Atl. LXXI f. 39. 



Fresh water: Arctic America! Beeren Eiland (Lagst.), Spitzbergen! 



52. C. cymbiformis (Ag. 1830?) Kutz. (1833). — V. boat-shaped, with straight, sometimes 

 slightly gibbous, ventral margin and obtuse or truncate ends. L. 0,0.5 to 0,i; B. 0,oi to 0,oi2 

 mm. Median line slightly arcuate, broad (oblique); its terminal fissures reflexed. Axial area 

 narrow; central area small. Strise 8 to 9 in 0, 01 mm. somewhat closer at the ends, finely lineate 

 (lineolfe 20 in 0,oi mm.). On the ventral side of the central nodule is an isolated punctum at the 

 end of the median stria. — Ag. Consp. p. 10 (1830)? Frustulia coffewformis Kutz. Dec. N:o 11 

 (1833) according to Lagst. Frust. cymb.[ Kutz. Linn. VIII p. 539 PL XIII f. 10. Coecon. cymbi- 

 forme W. Sm. B. D. 1 p. 76 PL XXIII f. 220? A. S. Atl. IX f. 76 to 79; X f. 13. Cymb. cymbif. 

 V. H. Syn. p. 63 PL II f. 11 a, b, c. 



Fresh water: Iceland! Norway (Finmark to Brevig)! Sweden! Finland! England! Belgium 

 (V. H.), France! Germany! Switzerland! Hungary (Dubravica, foss. Grun.), Socotra (Kitton), Japan! 

 Tasmania! Argentina! 



C. cymbiformis is very similar to C. helvetica, but differs by the reflexed terminal fissures 

 and from C. helvetica, as well as from C. parva, by the isolated punctum below the central nodule. 



53. C. Beccarii Grun. (1886). — V. clavate, and at the same time boat-shaped, with one 

 half longer than the other. L. 0,054 to O.oe; B. 0,oi4 mm. Median line arcuate, almost in the 

 middle of the valve. Axial area narrow, not dilated around the central nodule. Strise 11 to 16 



