KdNGL. SV. VET. AKADEMIEN.S HANDLINGAR. 



BAN 



!) 26. 



N:o 



153 



in 0,0 1 mm. at the ends), tlie 4 to 5 median strige, being stronger and more radiate than tlie others, 

 which become transverse towards the ends. Connecting zone vvith nnmerous longitudinal divisions. 

 Frustnles enclosed in mn(>ous tnbes of varions shape. — Scliunnema Grev. Aa. Consp. p. 18. W. 8m. 

 B. D. II p. 77 Pl. LVIII f. 3(i4. Grun. A. D. p. 42. V. H. Syn. p. 110 Pl. XVI f. 2. Srhkonema 

 seciio comoidea Grun. Bot. Centr. 1880. Schis. ennioiäes V. H. Syn. XVI f. 3. Srldz. apiculatmn 

 and var. V. H. Syn. 1. c. f. 4—8. Navic. Delocpiei V. H. Syn. p."llO Pl. XI f. 13. 



Marine: Spitsbergen! Finmark! North Sea! Coasts of England (Sm.), Arctic America! Green- 

 land! Cape Desclineff (North Siberian Sea)! West Indies! Kergnelens Land! California! 



N. Grevillei is closelj^ connected with N. rhomhica, and it is qnestionable wliether they 

 .shonld not be nnited. A great number of species of Schizonema have been fonnded on the shape 

 of the gelatinons tnbes, in -which tlie frustules are enclosed in the living state. As the frustnles 

 of these forms are in all essential respects similar, there seems to be no sufficient reason for 

 adopting these species. 



38. N. Libelliis Greg. (1857). — V. rhombic-lanceolate, convex, v?ith acute ends. L. O.oes 

 to 0,15; B. 0,016 to 0,03.5 mm. Terminal nodnles near the ends; terminal fi.ssnres indistinct. Axial 

 and central areas indistinct. Striee 13 to 14 in 0,oi mm., on larger form, or abont 18 inO,oi mm. 

 on smaller forms, very slightly radiate, almost parallel at the ends, distinctly pnnctate, pnncta 

 (13 to 16 in 0,01 mm.) forming undulating, longitudinal rows. Connecting zone with numerous, 

 longitudinal divisions. — Greg. D. of Cl. p. 528 Pl. XIV f. 101. N. rhomUca Donk. B. D. Pl. IX f. 1. 



Marine: Scotland (Greg.), Macassar Straits! Oamaru, fossil! Sendai, Japan, fossil! 



K. Lihellus is yerj similar to K. rJioiiihica, bnt has the terminal nodnles closer to the ends 

 and the striee almost parallel at the ends. The terminal fissnres are difficult to ohserve as the 

 ends of the valve are curved downwards. 



39. N. (Libellns) complanata Grun. (1867). — V. linear-lanceolate, acute. L. 0,035; B. 

 0,005 mm. Strice 18 to 19 in 0, 01 mm. Frustule rectangular. L. 0,054; B 0, 033 mm. Connecting 

 zone with numeroiis, longitudinal divisions. — Aniphora complanata Grun. Hedwigia A^^I p. 25. 



A. S. Atl. XXVI f. 45. Navic? compj. Grun. A. D. p. 42 (1880). 



Marine: Davis Strait! Sea of Kära (Grun.), Finmark! Bohu.slän! Adriatic (Grun.). 

 Var. suhinflata Grun. (1875). — Frustule rectangular. L. 0,04; B. 0,oi2 to 0,oi8 mm. 

 Slightly inflated in the middle. — Amphm-a subinfl. Grun. A. S. Atl. XXVI f. 48, 49. 

 Marine: Adriatic (Grun.). 

 Var. hijperhorea Gkun. (1884). — Frustule rectangular. L. 0,0 5; 



B. 0,0 165 mm. Strife 24 in 0,oi mm. — Amp)hora. hyprrhorea Grt^n. 

 Franz Josephs Land D. p. 55 (3) Pl. I f. 10. 



Marine: Franz Josephs Land (Grun.), Sweden, Fiskebäckskil! 



Nav. com2)lanata is nearly akin to N. Lihellus, but is no Am- 

 phora, though the frustules have some resemblance to that genus. 

 The valves are rarely met with and difficult to observe. N. sub- 

 inftata. and hyperhorea are scarcely specifically distinct. 



The living frustule has two chromatophore-plates, each ex- 

 tending along the connecting zone from the ends towards the central 

 nodule. 



40. N. (Libellus) Hyalosira Cl. (1822). — V. convex, thin, N. complanata with ceii-contents 

 lanceolate, rostrate or with rounded ends. L. 0,025 to 0,03; B. 0,oo66 ^^ *'■""' magnified. 



mm. StriiE 29 in 0, 01 mm. pnnctate. Frustule .slightly siliceous, quadrate. L. 0,025; B. 0, 01 7 mm. 

 Connecting zone broad, with numerous and distant longitudinal divisions. — Cl. M. D. N:o 309. 

 Diatomiste I p. 77 Pl. XII f. 11. 



Marine: Firth of Tay! Cresswell (Deby Coll.)! 



K. Sv. Vet. Akad. Handl. Bd 26. N:o 



20 



