18 P. T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



f. 352 (1856). ScUzon. neglectum V. H. Syn. Pl. XV f. 37. N. gracilis v. scUzon. V. H. Syn. p. 83 

 Pl. Vn f. 9, 10. 



Fresh -watei^: England! Belgium (V. H.). 



N. gracilis is very similar to larger varieties of N. cincta and to some forms of JSf. radiosa 

 from which it may be distinguisted by its less radiate strise, and larger, transverse central area. 



12. N. peregrina Ehb. (1843). — V. lanceolate with obtuse ends. L. 0,o8 toO.is; B. 0,o2i 

 to 0,028 mm. Axial area distinct, narrow. Central area large, somewhat transverse, subrectan- 

 gular. Striee in the middle 5 to 6 in 0,oi mm. radiate, and frequently alternately longer and 

 sborter, towards the ends transverse, and at the ends (8 in O, o imm.) convergent, distinctly lineate'; 

 lineolse about 25 in 0,oi mm. — Finn. pereg. Ehb. Am. 1: i f. 5, 6. W. Sm. B. D. I Pl. XVIII 

 f. 170. N. pereg. Kutz Bac. p. 97 Pl. 28 f. 52. A. S. Atl. XL VII f. 57—60. 



Brackish water: Sea of Kära! Baltic! North Sea! Saxony! Adriatic (Grrun.), Arctic America! 

 Greenland! Atlantic coasts of United States! Argentina! Cape Wankarema! Japan! Batavia! 



Var. kefvingensis Ehb. (1840). — Smaller. L. 0,044 to 0,09 mm. Striee 7 (middle) to 8,5 

 (ends). — Finn. kefv. Ehb. Ber. 1840 p. 20 (accord. to Kutz). M. Gr. X: 2, f. 4, 5. Nav. kefv. 

 Kutz Bac. p. 97 (1844). A. S. Atl. XLVII f. 61, 62. 



Brackish water: Eix^th of Tay! Franzenbad, fossil! 



Var. polaris Lägst. (1873). — V. subelliptical, with broad, obtuse ends. L. 0,o5i to 0,072; 

 B. 0,014 to 0,016 mm. Strise 6 (middle) to 8 (ends) in 0,oi mm. — N. polaris Lägst. Spitsb. D. 

 p. 24 Pl. II f. 3. Boh. p. 33. 



Brackish water: Spitsbergen! Beeren Eiland (Lägst.), Bohuslän (Lägst.). 



Var. calcuttensis Grun. Ms. — V. lanceolate. L. 0, 05 to 0,06; B. 0,oi7 mm. Strise 9, lineolse 

 21 in 0,01 mm. Axial area unilateral, not dilated in the middle. Central area small, also uni- 

 lateral. — Pl. II f. 2. 



Brackish water: Calcutta! 



Var. Meniscus Schum. (1867). — V. elliptic-lanceolate. L. 0,o36 to 0,o66; B. 0,oi to 0,oi9 

 mm. Strise 7 to 8,5 in 0,oi mm. — N. Meniscus Schdm. P. D. II N. p 55 Pl. II f. 32 {N. Sam- 

 biensis f. 37? N. aperta f. 49, N. Cyprinus f. 50?). Grun. A. D. p. 33. A. S. Atl. XLVII f. 47 

 (without name). N. pereg. v. 31. V. H. Syn, p. 82 Pl. VIII f. 19. 



Brackish water: Sea of Kära (Grun.), Baltic (Schum., Grun.), Königsberg, fossil! Cuxhaven 

 (Atl.), Cape Wankarema! 



Forms with asymmetrical axial area occur at Cape Wankarema. 



Var. Menisculus Schum. (1867). — V. elliptic-lanceolate, frequently slightly rostrate. L. 0,oi8 

 to 0,04; B. 0,01 to 0,011 mm. Axial area indistinct; central area small. Strise 9 to 12 in 0, 01 

 mm., fineiy lineate. — N. Menisc, Schum. P. D. II N. p. 56 Pl. II f. 33. N. pereg. v. Menisculus 

 V. H, Syn. p. 82 Pl. VIII f. 20, 21, 22. N. Gästrum v. IJpsaliensis Grun. in Cl. M. D. N:o 242. 

 N. pereg. menisculus f. Upsaliensis V. H. Syn. p. 82 Pl. VIII f. 23, 24. i\^. pressa, Pant. Ill 

 Pl. XXIV f. 362 (1893)? 



Fresh and slightly brackish water: Sweden! Baltic! Königsberg and Domblitten, fossil! Bel- 

 gium (V. H.), France (Paris, Normandy)! Saxony! Vienna (Gran.), Argentina (Sierra Velasco)! 



By the var. Menisculus N. peregrina seems to pass into N. cryptocephala, var. veneta. 



13. N. Haueri Grun. (1882). — V. lanceolate, with obtuse ends. L. 0,o8 to 0,12; B. 0,oi7 to 

 0,019 mm. Axial area narrow. Central area large, transverse. Strise 8 in 0, 01 mm. radiate and 

 more distant in the middle, convergent in the ends, hnely lineate, and crossed on both sides of the 

 median line by a narrow, blank area. — F. I). Öst. Ung. p. 143 Pl. XXX f. 48. Pant. III 

 Pl. VIK f. 135. 



Brackish water: Hiingary, fo.ssil (Dubravica, Grun., Bory)! 



This species, distinguished by the blank band across the strise, is nearly akin to N. peregrina. 



