KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 26. N:o 2. 133 



3. N. perpusilla GtRdn. (1860). — V. subelliptical, gibbous in the middle and with broad, 

 subtruncate ends. L. 0,012; B. 0,oo4 to 0,oo5 mm. Area lanceolate, narrow. Strise about 30 in 

 0,01 mm., radiate throughout. — 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 Smaland) ! 

 Finland (Lapland to Abo)! Arctic America! 



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

 0,005 to 0,0 7 mm. Area lanceolate. Striae 20 to 22 in 0,oi mm. radiate throughout, finely- 

 punctate. Frustules cohering in long bands. — Kutz Bac. p. 109 PL XXX f. 8. Gkun. Novara 

 p. 21 PL I f. 19. N. (Diad.) conf. V. H. Syn. XIV f. 36. 



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



Var. peregrina W. Sm. (1861). — V. ellipticaL L. 0,oi2 to 0,oi5; B. 0,oo6 to 0,oo6 5 mm. 

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

 New. confervacea var. peregrina, et hungarica Grun. in V. fl. Syn. PL XIV f. 37, 38. 



Fresh water: Eangoon! 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. Striae 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 diff'erence being that the strise of the former are less radiate. 

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

 0,01 mm., 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 Flacentula. Another small form of about the 

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

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

 form is N. debilis Pant. Ill 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. inflrma Grun. (1882) — V. linear elliptical, with rounded ends. L. 0,02; B. 0,oo7 mm. 

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

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



Fresh water: Hungary 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. Strise 19 to 21 in 0,o 1 mm. at the 

 middle, 23 to 24 in 0,oi mm. at the ends, almost parallel. — Grun. A. D. p. 46 PL III f. 66. 

 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. Ill PL XXXIX f. 538 (1893)? 



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

 Cape Horn! 



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

 illusion, arrising from the convexity of the valve. This species forms a passage from this group 

 to the section N. fusiforraes, which has no distinct area, parallel striae, 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 0,0 12 mm. Axial area narrow. Strise 21 to 25 in 0,oi mm. slightly 

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

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



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



