KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 26. N:0 2. 1.S3 



3. N. pei*piisilla (Irun. (1860). — V. subelliirtical, gibbous in the middle. and with broad, 

 subtruncate ends. L. 0,012; B. 0, 004 to 0,oor) mm. Area lanceolate, narrow. Strife about 30 in 

 0,01 mm., radiate thronghout. — Grun. Verb. 1860 p. 552 Pl. IV f. 7. V. H. Syn. Pl. XIV f. 22, 23. 



Fresh water (on moist rocks, earth etc): Scotland (Aberdeen)! Sweden (Taberg in Småland)! 

 Finland (Lapland to Abo)! Arctic America! 



4. N. (Diadesmis) coufervacea Kutz (1844). — V. thick, lanceolate, obtuse. L. 0,02; B. 

 0,005 to 0,00 7 mm. Area lanceolate. Striis 20 to 22 in 0,oi mm. radiate throiighout, finely 

 punctate. Frustules cobering in long bands. — KtJTZ Bac. p. 109 Pl. XXX f. 8. (tRUN. Novara 

 p. 21 Pl. I f. 19. N. (Biad.) conf. V. H. Syn. XIV f. 36. 



Fresb water, tropics: Jamaica! Rio Janeiro! Marquesas Island! Sandwich Islands! 



Var. pereyrina W. Sm. (1861). — V. elliptical. L. 0,012 to 0,oi5; B. 0,oo6 to 0,oo6s mm. 

 Strise 22 in 0,oi mm. — Diadesmis peregrina Pritch Inf. p. 923. G-rdn. Novara Pl. I f. 20. 

 Nav. conferi-acea var. peregrina, et hungarica Grun. in V. fl. Syn. Pl. XIV f. 37, 38. 



Fresh water: Rangoon! Australian Alps (Riewa Lagoon)! Tahiti (Grnn.), Jamaica! Ecuador' 



5. N. Scutum (ScHUM.?) V. H. (1880). — V. narrow elliptical, with rounded ends. L. 0,03; 

 B. 0,01 mm. Area narrow, lanceolate, dilated around the central nodule. StriiB 16 in 0,oi mm., 

 very slightly radiate, finely punctate. — Schum. Pr. D. p. 188 f. 45 (1862)? V. H. Syn. p. 98 

 Pl. XI f. 14. 



Fresh water: Belgium (V. H ). 



N. Scutum V. fl. and N. infirma Grun. are, as far as I may judge from the descriptions 

 and the figures, closely akin, the only difFerence being that the strite of the former are less radiate. 

 The Nav. Scutum. Schum. from the Königsberg deposit bas about the same size, and 14 strise in 

 0,01 mm., but no area, so it seems doiibtful whether it be tlie same species as Van Heurck's. The 

 Nav. Scutum Schum. is perhaps a form of Cocco)ieis Flacentula. Another small form of about the 

 same outline and size and with 15 parallel strise in 0, 01 mm., but without area is Nav. ignobilis 

 Pant. (II p. 48 Pl. XXV f. 367, 1889) from the brackish strata of Kavna, Hiingary. A similar 

 form is N. debilis Pant. III Pl. VI f 98. Having had no opportunity of examining these forms I 

 am unable to decide whether or not they are identical. 



6. N. infirma Grun. (1882) — V. linear elliptical, with rounded ends. L. 0,02; B. 0,oo- mm. 

 Area narrow, lanceolate. Strise 13 (middle) to 17 (ends) in 0, 01 mm. radiate throughout and finely 

 punctate. — Grun. Foss. D. Öster. Ung. p. 146 Pl. XXX f. 53. 



Fresh water: flungary fossil (Dubravica Grun.). 



7. N. inornata Grun. (1880). — V. fusiform, convex. L. 0,o5 to 0,09; B. 0,o88 mm. Median 

 line with approximate central pores. Area narrow, lanceolate. Striaj 19 to 21 in 0, 01 mm. at the 

 middle, 23 to 24 in 0,oi mm. at the ends, almost parallel. — Grun. A. D. p. 46 Pl. III f. 56. 

 N. Acus Cl. A. D. p. 14 Pl. III f. 55. N. Hahnii Petit Cape Horn D. p. 124 Pl. X f. 11 (1888). 

 N. filiformis Pant. III Pl. XXXIX f. 538 (1893)? 



Marine: Finmark! Bohuslän! Mediterranean (Pithuisian Island)! lie de Brehat, Manche! 

 Cape Horn! 



N. iyiornata seems to have a longitudinal line crossing the strise, but this line is an optical 

 illusion, ari-ising from the convexity of the valve. This species forms a passage from this group 

 to the section N. fusiformes, which has no distinct area, parallel strise, and very approximate 

 central pores. 



8. N. fusoides Grun. (1880). — V. narrow, linear-lanceolate, with more or less obtuse ends. 

 L. 0,05 to 0,12; B. 0,007 to 0,012 mm. Axial area narrow. Strite 21 to 25 in 0, 01 mm. slightly 

 radiate, crossed by two longitudinal lines. — N. suhula Grun. Verh. 1860 p. 548 Pl. III f. 24. 

 N. fusoides Grun. A. D. p. 46. 



Marine: Bohuslän (Grun.), Mediterranean Sea (Grun.). 



