KONGL. SV. VET. AKADI<:MIKNS HANDLINGAH. RAND 26. N:0 2. 133 



3. N. perpiisilla Grun. (18(i()). - V. subelliptical, gibbous in tho middlp and with broad, 

 subtruncate ends. L. 0,012; B. 0,oo4 to (),0()r> mm. Area lanceolate, narrow. StrifK about 30 in 

 0,0 1 mm., radiate throughout. — Grun. Verb. 1860 j). 552 PI. IV f. 7. V. H. Syn. PI. XIV f. 22, 23. 



Fresh water (on moist roeks, earth etc.): Scotland (Aberdeen)! Sweden (Taberg in Smaland)! 

 Finland (Lapland to Abo)! Arctic America! 



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

 0,005 to 0,007 mm. Area lanceolate. Strife 20 to ^li in 0,oi mm. radiate throughout, finely 

 punctate. Frustules cohering in long bands. — KtJTZ Bac. p. 100 PI. XXX f. 8. Grun. Novara 

 p. 21 PI. I f. 19. N. (Diacl.) conf. V. H. Syn. XIV f. 36. 



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



Var. pere(jrina W. Sm. (1861). — V. elliptical. L. 0,012 to 0,015; B. 0,oo6 to 0,0065 mm. 

 Striae 22 in 0,oi mm. — Diadesmis peregrina Pritch Inf. p. 923. Grun. Novara PI. I f. 20. 

 Nav. confervacea var. peregrina, et hungarica Grun. in V. H. Syn. PI. XIV f. 37, 38. 



Fresh water: Rangoon! Australian Alps (Riewa Lagoon)! Tahiti (Grun.), 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. Strite 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. H. 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 stricB of the former are less radiate. 

 The Nav. Scutum Schum. from the Konigsberg deposit has about the same size, and 14 strite in 

 0,01 ram., but no area, so it seems doubtful whether it be the same species as Van Heurck's. The 

 Nav. Scutum Schum. is perhaps a form of Cocconeis Flacenfula. Another small form of about the 

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

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

 form is N. dehiUs Pant. Ill PI. 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,oo7 mm. 

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

 punctate. — Grun. Foss. D. Oster. Ung. p. 146 PI. XXX f. 53. 



Fresh water: Hungary fossil (Dubravica Grun.). 



7. N. inornata Grun. (1880). — V. fusiform, convex. L. 0,o5 to0,o'.); B. 0,o88 mm. Median 

 line with approximate central pores. Ai-ea narrow, lanceolate. Striae 19 to 21 in 0,oi mm. at the 

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

 N. Acus Cl. a. D. p. 14 PI. Ill f. 55. N. Hahnii Petit Cape Horn D. p. 124 PI. X f. 11 (1888). 

 N. filiformis Pant. Ill PI. XXXIX f. 538 (1893)? 



Marine: Finmark! Bohuslan! Mediterranean (Pithuisian Island)! He de Brehat, Manche! 

 Cape Horn! 



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

 ilhision, arrising 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 striae, and very approximate 

 central pores. 



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

 L. 0,05 to 0,12; B. 0,00 7 to 0,012 mm. Axial area narrow. Striif 21 to 25 in 0,oi mm. slightly 

 radiate, crossed hy two longitudinal lines. — N. suhula Grun. Verb. 1860 p. 548 PI. Ill f. 24. 

 N. fusoides Grun. A. I), p. 46. 



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



