40 P- T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



.„ / Central area large N. Grovei Cl. 



*"*■ \ — - small 44. 



Strise crossed by a blank band N. interlineata Grove a. Sttjrt. 



{ 



I — not — — — 45. 



., I Valve witb sballow depressions on each side of the median line .... N. impressa Grun. 



\ — without 46. 



.„ / Median portion of tbe valve elevated at the ends N. carinifera Gbun. 



* \ - - - not - - 47. 



«.j 



Stri» radiate 48. 



almost parallel 49. 



.„ j Puncta equidistant N. punctulata W. Sm. 



\ — closer at the margin and axis N. brasiliensis Grun. 



,p / Striae 9 in 0,oi mm .50. 



^^- t - 11 to 14 - 51. 



p.^ ( Central area orbioular N. doljensis Pant. 



■ ( — — transverse N. Brunii Pant. 



_.. f Valve rhombic-lanceolate N. Pi Cl. 



\ — elliptio-lanceolate N. scandinavica Lägst. 



1. N. scutelloides W. Sm. (1856). — V. orbicular. L. 0,oi5 to 0,027; B. 0,oi3 to 0,02 mm. 

 Axial area indistinct; central area indistinct or irregular. Strise 10 iu 0, 01 mm. radiate through- 

 out, the median striee of unequal length. Puncta of the strise coarse, 10 in 0,oi mm. — M. J. IV 

 Pl. I f. 15. — ScHUM. Pr. D. I N. p. 20 f. 22. A. S. Atl. VI f. 34. Ströse Klieken Pl. I f. 11. 



Fresh and slightly brackish water: Sweden (Gulf of Bothnia! Lake Mälaren! Ronneby, 

 fossil! etc), Finland, fossil! Germany, Domblitten, foss. (Atl.), England! 



Var. mocarensis Geun. (1882). — Strise very distant, alternating with short, marginal strise. 

 — Foss. D. Öst. Ung. Pl. XXX f. 65. 



Fresh water: Hungary, fossil (Grun.). 



Var. minutissima Cl. (1881). — Diam. 0,oo8 mm. Strise obsolete. — D. f. Grönl. Argentina 

 p. 12 Pl. XVI f. 10. 



Fresh water: Greenland! Finland. 



2. N. sciutillans A. S. (1881). — V. elliptical, with broad, rounded ends. L. 0,038; B. 0,026 

 mm. Axial area indistinct; central area small, somewhat transverse. Strise 10 (middle) to 12 

 (ends) in 0,oi mm. in the middle of unequal length, coarsely punctate, the puncta in the middle 

 of the valve larger. — Atl. LXX f. 61. 



Marine: Campeachy Bay. 



3. N. neogradensis Pant. (1886). — V. elliptic-lanceolate. L. 0,057; B. 0,o34 mm. Axial 

 area narrow; central area indistinct. Strise 7 in 0, 01 mm., radiate throughout, alternating with 

 short marginal striolse. Puncta of the strise 7 in 0, 01 mm. — Cocconeis neogr. Pant. I p. 31 

 Pl. XIII f. 111. 



Marine: Hungary, fossil (Pant.). 



There is no reason for placing this species in Cocconeis. It seems nearly akin to Nav. 

 punctulata, and to the foUowing. 



4. N. algida Grun. (1884). — V. broadly elliptical, with rounded ends. L. 0,07 to 0,o85; 

 B. 0,0 3 5 to 0,0 4 mm. Axial area very narrow. Central area not well defined, the median part 

 of the valve being an irregular space with scattered puncta. StriiB 9 to 10 in 0, 01 mm., radiate 

 throughout, coarsely punctate, alternating with short marginal striolfe. — Fr. Jos. Land D. p. 56 

 Pl. I f. 31. Nav. glacialis Cl. M. D. N:o 302, Vega p. 471. 



Marine: North Siberian Sea! 



5. N. glacialis Cl. (1873). — V. elliptical. L. 0,o6 to 0,ii; B. 0,03 to O.oee mm. Axial 

 area linear, narrow. f'eiitral area orbicular. Striie 12 in 0, 01 mm., radiate throughout, punctate; 



