40 p. T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



.„ . Central area large N. Grovei Cl. 



small 44. 



J Central are; 

 StriaB crossed by a blank band N. interlineata Grove a. Stuet. 



{ 



Median portion of the valve elevated at the ends N. carinifera Grun. 



44. 



not — — — 45. 



.J. ( Valve with shallow depressions on each side of the median line .... N. impressa Grun. 



) — without _ 46. 



46- > 



— — not — — 47 



Striae radiate 48 



— almost parallel 49 



47. <j 



.„ i Puncta equidistant N. punctulata W. Sm 



closer at the margin and axis N. brasiliensis Grun. 



( Striae 9 in 0,oi mm 50. 



t — 11 to 14 — 51. 



j Central area orbicular N. doljensis Pant. 



\ — — transverse N. Brunii Pant. 



ve rhombic-lanceolate N. Pi Cl. 



elliptic-lanceolate N- scandinavica Lagst. 



51. {^^ 



1. N. scutelloides W. Sm. (1856). — V. orbicular. L. 0,oi5 to 0,027; B. 0,01.3 to 0,02 mm. 

 Axial area indistinct; central area indistinct or irregular. Stria; 10 in 0,oi mm. radiate through- 

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

 PI. I f. 15. — ScHUM. Pr. D. I N. p. 20 f. 22. A. S. Atl. VI f. 34. Strose Klieken PL I f. 11. 



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

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



Var. mocarensis Grun. (1882). — Strite very distant, alternating with short, marginal striae. 

 — Foss. D. Ost. Ung. PL XXX f. 65. 



Fresh water: Hungary, fossil (Grun.). 



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

 p. 12 PL XVI f. 10. 



Fresh water: Greenland! Finland. 



2. N. sciiitillans A. S. (1881). — V. elliptical, with broad, rounded ends. L. 0,o38; B. 0,o26 

 mm. Axial area indistinct; central area small, somewhat transverse. StricE 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. 0,034 mm. Axial 

 area narrow; central area indistinct. StricB 7 in 0,oi mm., radiate throughout, alternating with 

 short marginal striola;. Puncta of the strite 7 in 0,oi 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 following. 



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

 B. 0,035 to 0,04 mm. Axial area very narrow. Central area not well defined, the median part 

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

 throughout, coarsely punctate, alternating with short marginal striolffi. — 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 0,o66 mm. Axial 

 area linear, narrow. Central area orbicular. Strise 12 in 0,oi mm., radiate throughout, punctate; 



