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



.„ ( Central area large N. Grovei Cl. 



■ \ — — small 44. 



. , f Striae crossed by a blank band N. interlineata Gbovb a. Stubt. 



**• \ _ not - - - 45. 



.f. I Valve with shallow depressions on each side of the median line .... N. impressa Geun. 



\ — without .... 46. 



. „ ( Median portion of the valve elevated at the ends N. carinifera Geun. 



*^- \ - - - not - - 47. 



.„ / Striae radiate . . . . 48. 



\ — almost parallel . 49. 



.„ f Puncta equidistant .... ... . . . . N. punetulata W. Sm. 



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



.„ / Striae 9 in 0,ni mm . . 50. 



\ - 11 to 14 - 51. 



p,^ / Central area orbicular N. doljensis Pant. 



' I — — transverse . . . N. Brunii Pant. 



/ Valve rhombic-lanceolate . . . . . N. Pi Cl. 



51 < 



\ — elliptic-lanceolate JV. scandinavica Lagst. 



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 in 0,oi mm. radiate through- 

 out, the median strise 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. Strose Klieken PL I f. 11. 



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

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



Var. mocarensis Gtrun. (1882). — Striae 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. G-ronl. Argentina 

 p. 12 PL XVI f. 10. 



Fresh water: Greenland! Finland. 



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

 mm. Axial area indistinct; central area small, somewhat transverse. Striae 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. Striae 7 in 0,oi mm., radiate throughout, alternating with 

 short marginal striolae. Puncta of the striae 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. 

 punetulata, and to the following. 



4. N. algida Grun. (1884). — V. broadly elliptical, with rounded ends. L. 0,07 to 0,08.5; 

 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. Striae 9 to 10 in 0,oi mm., radiate 

 throughout, coarsely punctate, alternating with short marginal striolae. — 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. glacialjs Cl. (1873). — V. ellipticaL L. 0,o6 to 0,ii; B. 0,03 to 0,o66 mm. Axial 

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



