20 p. T. CLEVE, SYNOPSIS OF THE NAVICULOIU DIATOMS. 



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

 Terminal striae transverse. — Pant. II p. 51 PL V f. 95. 

 Brackish water: Hungary, fossil! 



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

 L. 0,07; B. 0,026 mm. Axial area narrow. Central area subrectangular. Striee 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 PI. I f. 36. 



Fresh water: Franz Josefs Land (Grrun.). 



21. N. bottnica G-run. (i880). — V. lanceolate, obtuse. L. 0,o4 to 0,o6 5; B. 0,oi to 0,oi3 

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

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



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



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

 land! Canada! Maine! 



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

 0,018 mm. Axial area narrow. Central area small, irregular. Striae 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. angustior Grun. A. D. PL II f. 31. 



Marine and brackish: Spitsbergen! Finmarken! Sea of Kara! 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 0,0 8; B. 0,0125 to 0,02 7 5 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. Striae 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. 0,065; B. 0,02 mm. Striae 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. 0,014 to 0,017 mm. Axial area very narrow. Central area irregular, trans- 

 versely dilated. Striae 9 in 0,oi mm., coarsely lineate, in the middle alternately longer and 

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

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

 p. 86 PL VII f. 5, 6. Stauroptera 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,o6 to 0,07; 



B. 0,0 13 mm. Striae 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. jenisseyensis Grun. (1880). — As. var. gracilior, but with only few shorter median striae. 

 L. 0,132; B. 0,016 mm. A. D. p. 32. 



Fresh water: Mouth of Jenissey (Grun.). 



N. Reinhardtii is veiy similar to N. digito-radiata, from which it differs by its fresh water 

 habitat, and its more coarsely lineate striae, and to N. Gastrum, which has striae radiate throughout. 



