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



f. 352 (1856). Schison. negUctum V. H. Syn. PI. XV f. 37. N. gracilis v. schison. V. H. Syn. p. 83 

 PL Vn f. 9, 10. 



Fresh water: England! Belgium (V. H.). 



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

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



12. N. peregrina Ehb. (1843). — V. lanceolate with obtuse ends. L. 0,o8 to0,i5; B. 0,02i 

 to 0,02 8 mm. Axial area distinct, narrow. Central area large, somewhat transverse, subrectan- 

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

 shorter, towards the ends transverse, and at the ends (8 in 0,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 PI. XVIII 

 f. 170. i\^. pereg. KtJTz Bac. p. 97 PL 28 f. 52. A. S. Atl. XLVII f. 57—60. 



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

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



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

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

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



Brackish water: Firth of Tay! Franzenbad, fossil! 



Var. polaris Lagst. (1873). — V. subelliptical, with broad, obtuse ends. L. 0,0 5i to 0,072; 

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

 p. 24 PL n f. 3. Boh. p. 33. 



Brackish water: Spitsbergen! Beeren Eiland (Lagst.), Bohuslan (Lagst.). 



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 Schum. P. D. II N. p 55 PL II f. 32 (JSf. 8am- 

 iiensis 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. M. V H. Syn. p. 82 PL VIII f. 19. 



Brackish water: Sea of Kara (Grun.), Baltic (Schum., Grun.), Konigsberg, 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,oi 

 mm., finely lineate. — N. Menisc, Schum. P. D. II N. p. 5(5 PL II f. 33. N. pereg. v. Menisculus 

 V. H. Syn. p. 82 PL VIII f. 20, 21, 22. N. Gastrum v. Upsaliensis Grun. in CI. M. D. N:o 242. 

 N. pereg. menisculus f. Upsaliensis V. H. Syn. p. 82 PL VIII f. 23, 24. N. pressa Pant. Ill 

 PL XXIV f. 362 (1893)? 



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

 gium (V. fl.), France (Paris, Normandy)! Saxony! Vienna (Grun.), Argentina (Sierra Velasco)! 



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



13. N. Haueri Grun. (1882). — V. lanceolate, with obtuse ends. L. 0,o8 to 0,12; B. 0,017 to 

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

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

 median line by a narrow, blank area. — F. I). Ost. Ung. p. 143 PL XXX f. 48. Pant. Ill 

 PL VIII f. 135. 



Brackish water: Hungary, fossil (Dubravica, Grun., Bory)! 



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



