KONGL. SV. Vl-yr. AKADEMIENS IIANDMNOA 1{. HAM) 27. 



\:ii 



J. ( Puncta forming lonsitndiiuil rows jianilli'l to the inarf;iiis of tlic valvi' . . . iV. Theta Cu. 

 \ — not — — - — — — y. HcAitiformin Grun. 



. I Striae very fini'. about ."SO Iti 0,oi nun K. Pusio <h.. 



\ — coarser. al>ont 17 in O.ni nun jY. sitrinnmerisis Ci,. 



1. N. Theta Cl. (189;)). — V. elliptical. L. 0,o.'>.5; B. 0,028 lum. Axial area narrow, 

 linear; central area small, orbicular. Stritxi radiate (in tlie ends nearly parallel) in the middle, 

 where they are altei-nately longer and shorter, 20 in (),iii nun. at the ends 2h in O.di nun., di- 

 stinctl}' punctate; puncta 21 in 0,01 mm. forming longitudinal rows parallel with the margin. — 

 Diatomiste II p. 5C PI. Ill f. 5. 



Fresh water: Oregon, fossil. 



2. N. limicolii Cl. (1893). — V. elliptical, with rounded, obtu.se ends. L. 0,04f. ; B. 0,017 

 mm. Axial area narrow, linear. Central area moderately large, orbiculai-. Striaj about 25 in 

 0,01 mm., gently curved and radiate at the ends, finely but distinctly punctate. Median striae 

 more coarsely pnnctate than the others. — Diatomiste II p. 14 PI. I f. 12. 



Moiith of rivers: Cameroon, Africa (leg. Dusen). 



3. N. Pusio Cl. N. Sp. — V. elliptical, with broad rostrate ends. L. 0,0 n,; B. 0,007 mm. 

 Axial area very narrow. Central area small. Strise very fine, about 30 in 0,oi mm. radiate at 

 the ends, in the middle alternately longer and shorter, closer towards the ends. — PI. II f. 3. 



Fresh water: Rotorua Lake, N. Zealand (leg. Berggren). 



N. arcuotn Pant. Ill PI. VI f. 97 represents a similar, but larger form. L. 0,o,t; B. 0,oi6 

 mm. Strije 27 in 0,oi mm. 



4. N. cocconeiforinis Greg. (1856). — V. elliptical to rhomboidal, obtuse. L. 0,026 to 

 0,032; B. 0,009 to 0,013 mm. Central pores of tlie median line distant. Axial area indistinct; 

 central area small, elongated. Strife 25 to 29 in 0,oi mm., radiate at the ends, in the middle of 

 unequal length, finely punctate. — M. J. IV, I. f. 22. (Irun. Verb. I860 p. 550 PI. IV f. 9. 

 DoNK. B. D. p. 22 PI. Ill f. 11. La(;st. Spitsb. D. p. 32 PI. II f. 8. V. H. Syn. PL XIV f. 1. 



Fresh water, especially in arctic or alpine regions: Spitsbergen! Norway, Dovre! Finland 

 (Russian Lappland to Abo), Sweden! Scotland! France (Vosges)! Oregon, fo.ss.! 



5. N. scutifonnis Grun. (1881). — V. ellij)tical, with broad, rounded ends. L. 0,04; B. 0,024 

 mm. Central pores of the median line distant. Axial area very narrow, linear; central area 

 large, orbicular. Striai 18 to 20 in 0,oi mm. (in the middle, closer towards the ends), strongly 

 radiate; the median of unequal length, not more coarsely punctate than the others. — A. S. Atl. 

 LXX f. 62. 



Fresh water: Stavanger, Norway (A. S. Atl.), Lule Lappmark! Umea. Sweden, fossil! 



6. N. Tail Cl. (1893). — V. elongated, slightly biconstricted, with cuneate ends. L. 0,037; 

 B. 0,01 mm. Axial area very narrow; central area of medium size, rounded. Strite 20 in 0,oi 

 mm. radiate at the ends; in the middle of unequal length. — Diatomiste II p. 14 PI. I f. 11. 



Fresh water: Demerara River! 



7. N. Sliriliamensis Cl. N. Sp. — V. elliptic-lanceolate with rostrate, broad ends. L. 0,027; 

 B. 0,0 13 mm. Median line with the terminal fissures in contrary direction. Axial area indistinct 

 or very narrow. Central area .small. Striae 17 in 0,»i mm., in the middle alternately longer and 

 shorter, radiate at the ends. — PI. II f. 1. 



Fresh water: Surinam! 



Koti)']. .Sv. Vet. Akad. Hsiiidl. Band 27. N:o 3. 



