20 P. T. 'CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



in 0,01 mm. more distant in the middle, where tliey are radiate and alternately longer and shorter. 

 Terminal strife transverse. — Pant. II p. 51 Pl. V f. 95. 

 Brackish water: Hungary, fossil! 



20. N. Wilczekii Gkun. (1884). — V. elliptic-lanceolate, with protracted, rostrate ends. 

 L. 0,07; B. 0,026 mm. Axial area narrow. Central area subrectangular. Strise 10 in 0,oi mm. 

 finely punctate, in the middle more distant (8 in 0,oi mm.) alternately longer and shorter, ra- 

 diate; strongly convergent at the ends, where they are closer (16 to 17 in 0,oi mm). — Franz 

 Jos. Land D. p. 98 Pl. I f. 36. 



Fresh water: Franz Josefs Land (Grun.). 



21. N. bottnica Grun. (i880). — V. lanceolate, obtuse. L. 0,o4 to O.oes; B. 0,oi to 0,oi3 

 mm. Axial area indistinct. Central area orbicular. Striie 20 in 0,oi mm. very iinely punctate, 

 in the middle strongly radiate and alternately longer and shorter, at the ends convergent. — 



A. D. p. 32 Pl. II f. 32. V. H. Syn. Pl. VII f. 33. 



Brackish and marine: Finmark! Coast of England! Baltic (from Piteå to Gothland)! Green- 

 land! Canada! Maine! 



22. N. digito-radiata Geeg. (1856). — V. lanceolate, obtuse. L. 0,06 to 0,o7; B. 0,oi2 to 

 0,018 mm. Axial area narrow. Central area small, irregular. Strise 9 in 0,oi mm., very finely 

 lineate, in the middle radiate and alternately longer and shorter, at the ends transverse. — Finn. 

 dig. M. J. IV Pl. I f. 32. N. dig. A. S. N. S. D. p. 92 Pl. IH f. 4. V. H. Syn. p. 86 Pl. VII f. 4. 

 Pinnul viridula Ehb. Abh. Berl. Ak. 1870 II f. 12. N. dig. v. angtistior Grun. A. D. Pl. II f. 31. 



Marine and brackish: Spitsbergen! Finmarken! Sea of Kära! North Sea! Saxony! Caspian 

 Sea (Grun.), Arctic America! New York! Fossil, Hungary (Grun.). 



Var. Cyprinus (Ehb. 1843?) W. Sm. (1853). — V. slightly gibbous in the middle. L. 0,o6 

 to 0,08; B. 0,0125 to 0,0275 mm. — Finn. Cypr. Ehb. Am. L 2 f. 7? W. Sm. B. .D. I Pl. XVIII 

 f. 176. N. digito-r. var. Cypr. V. H. Syn. p. 86 Pl. VII f. 3. 



Marine: North Sea! England (W. Sm.), Belgium (V. H.). 



Var. Seychellensis Cl. — As the type. L. 0, 04; B. 0,oi mm. Striee 12 to 13 in 0,oi mm. 



Marine: Seychelles (V. H. Coll.)! 



Under the name N. Gurovii Pantocsek (III Pl. IV f. 58) has figured a form, which seems 

 to be a new species, akin to N. digito-radiata or N. peregrina. It is broadly, almost rhomboid, 

 lanceolate. L. 0,o65; B. 0, 02 mm. Strise 6 in 0,oi mm. the median of unequal length. 



23. N. Reinhardtii Grun. (1860). — V. elliptical to lanceolate, with broad, obtuse ends. 

 L. 0,04 to 0,07; B. 0,0 14 to 0,017 mm. Axial area very narrow. Central area irregular, trans- 

 versely dilated. Strife 9 in 0, 01 mm., coarsely lineate, in the middle alternately longer and 

 shorter, strongly radiate, in the ends transverse. — Stauroneis Beinhardtii Grun. Verb. 1860 p. 566 

 Pl. VI f. 19. Nav. vernalis Donk. M. J. 1869 p. 293 Pl. XVIII f. 5. Nav. Beinh. V. H. Syn. 

 p. 86 Pl. VII f. 5, 6. Stanroptera truncata Rabh. Sussw. D. Pl. IX f. 12 (1853) Alg. Sachs. N:o 848. 



Fresh water: Sweden! England! Belgium (V. H.), Germany! Switzerland! 



Var. gracilior Grun. (1880). — V. lanceolate, narrowed towards the ends. L. 0,06 to 0,o7; 



B. 0,0 13 mm. Striee 8 to 9 in 0,oi mm. — N. digito-radiata var. striolata Grun. A. D. p. 32. 

 N. Reinh. var. gracilior V. H. Syn. p. 87. 



Fresh water, occurring with the type. 



Var. j('ni.'sscycnsis Grun. (1880). — As. var. gracilior, but with only few shorter median strife. 

 L. 0,132; B. O,oifi min. A. D. p. 32. 



Fresh water: Mouth of Jenissey (Grun.). 



N. Rnnhardfii is very similar to N. digito-radiata, fi'om whicli it differs by its fresh water 

 habitat, and its more cgarsely lineate striae, and to N. Gästrum, which has striae radiate throughout. 



