172 r. T. CLEVE, SYNOPSIS or THE NAVICUI.OIl» DIATOMS. 



Fresh water: Swedeii (Uppland to Skåne, Gothland, Gulf of Bothnia)! Finland! Holstein! 

 England! Belgium (V. H,), Germany! Switzerland! Italy! Month of Jenissey! Japan! Anstralia 

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



Cymi. affiiiis is a variable species, connecting Cynih. turgidula witli Cymb. parca. The 

 ventral margin is sometimes indented in the middle. SucL a form has been figured by Grukow in 

 Foss. Diat. Österr. Ung. Pl. XXIX f. 26 and is probably identical with Cymh. txiaa var. major 

 GuTwiNSKY Materialy p. 25 Pl. I f. 21. 



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

 trnncate ends. L. 0,03 to 0,05; B. 0,oi to 0,oi2 mm. Median line soraewhat arcnate and broad 

 (obliqne). Axial area narrow, very slightly dilated in the middle. Strite 9 or 10 (median, dorsalj 

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

 punctum on the ventral side of the central nodule. — Cocco. parvmii W. Sm. B. I). I p. 77. Pl. 

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

 formis var. luirva V. H. Syn. p. 64 Pl. II f. 14. Cocconema pachycephalum Rabh. Alg. Enr. 

 N:o 1107 (1861). 



Fresh water: Greenland! Franz Josephs Land (Grnn.), Sweden (Lapland to Skåne)! Norwaj^ 

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

 Italy! Month of Jenissey! North America, Winnepeg! 



Var. Imnyarica Grun. (1875). — L. 0,024 to 0,o4; B. 0,oo9 to 0,oi mm. Area dilated on 

 the dorsal side of the central nodule. Strise 10 in 0,ui mm. — Coccon. hungaric. Grun. in A. S. Atl. 

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



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



Cyinh. parva is in the living state stipitate. It is closely akin to Cynib. afjiins and 

 Cymb. cymhiformis, differiiig from botli by the want of a punctum at the end of the median 

 central stria. 



51. C. Botollus Lägst. (1873). — V. arcnate, with parallel margins and rounded ends. 

 L. 0,024 to 0,034; B. 0,oo6 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. Botdhis Lägst. Spitsb. D. p. 44 Pl. II f. 22. 

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



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



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

 slightly gibbous, ventral margin and obtuse or truncate ends. L. O, o 5 to 0,i; B. O.oi to 0,oi2 

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

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

 (lineohc 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)? Frustulki cojfcKformis IviiTZ. Dec. N:o 11 

 (1833) according to Lägst. Frust. cymb.\ IvtJTZ. Linn. VIII p. 539 Pl. XIII f. 10. Coccon. cymbi- 

 forme W. Sm. B. D. I p. 76 Pl. XXIII f. 220? A. S. Atl. IX f. 76 to 79; X f. 13. Cymb. cymhif. 

 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. heli-cfka, but difters by tlie reflexed terminal fissnres 

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



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

 half longer than the other. L. 0,o.')4 to 0,06; B. 0,oi4 mm. Median line arcuate, almost in the 

 middle of the valve. Axial area narrow, not dilated around the central nodule. Stria' 11 to 1(5 



