KONGL. SV. VET. AKADEMIENS IIANDLI X(iAl{. I'.AM) 26. N:o 2. 158 



in 0,01 mm. at the ends), the 4 to .") median stria' being stronger and more radiate than the others, 

 which become transverse towards the ends. Connecting zone with numerous longitudinal divisions. 

 Frustules enclosed in mucous tubes of various shape. — Schi.ionema (rirr. Ac. Consp. p. 18. W. Sm. 

 B. D. II p. 77 PI. LVII[ f. 3()4. Grfx. A. D. p. 42. V. H. Syn. p. 110 PI. XVI f. 2. Srhizonema 

 sedio comoidea Grun. Bot. C'entr. 1880. Schiz. comoides V. H. Hyn. XVI f. 3. Schiz. ajnculatum 

 and var. V. H. Syn. 1. c. f. 4—8. Navic. Bdoguci V. H. 8yn. p." 110 PI. XT f. 13. 



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

 land! Cape Deschneff (North Siberian Sea)! West Indies! Kerguelens Land! California! 



N. Grcvillei is closely connected with N. rhomhica, and it is (questionable whether they 

 should not be united. A great number of species of Schizonema have been founded on the shape 

 of the gelatinous ti^bes, in which the frustules are enclosed in the living state. As the frustules 

 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, with acute ends. L. 0,06.5 

 to 0,1.5; B. 0,0 iG to 0,03-) mm. Terminal nodules near the ends; terminal fissures indistinct. Axial 

 and central areas indistinct. Stria; 13 to 14 in 0,oi mm., on larger form, or about 18 in 0,oi mm. 

 on smaller forms, very slightly radiate, almost parallel at the ends, distinctly punctate, puncta 

 (13 to 1(5 in 0,01 mm.) forming undulating, longitudinal rows. Connecting zone with numerous, 

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



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



N. Lihellus is very similar to N. rliomhica, but has the terminal nodules closer to the ends 

 and - the strite almost parallel at the ends. The terminal fissures are difficult to observe as the 

 ends of the valve are curved downwards. 



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

 0,005 mm. Striae 18 to 19 in 0,oi mm. Frustule rectangular. L. 0,o54;B 0,0.33 mm. Connecting 

 zone with numerous, longitudinal divisions. — Amphora complanrita Grun. Hedwigia VI p. 25. 



A. S. Atl. XXVI f. 45. Ncivic? comj>l. Grun. A. D. p. 42 (1880). 



Marine: Davis Strait! Sea of Kara (Grun.), Finmark! Bohuslan! Adriatic (Grun.). 

 Var. suhinflata Grun. C1875). — Frustule rectangular. L. 0,04; B. 0,oi2 to 0,oi8 mm. 

 Slightly inflated in the middle. — Amphora suhhifl. Grun. A. S. Atl. XXVI f. 48, 49. 

 Marine: Adriatic (Grun.). 

 Var. hyperhorca Grun. (1884). — Frustule rectangular. L. 0,05; 



B. 0,0 105 mm. Stritii 24 in 0,oi mm. — ■ Amphora hyprrhorca Grun. 

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



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



Nar. compilanata is nearly akin to K. Lihellus., but is no Am- 

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

 The valves are rarely met witli and difficult to observe. K. suh- 

 hiflata and hyprrhorca are scarcely specifically distinct. 



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

 tending along the connecting zone from the ends towards the central 

 nodule. 



40. N. (Libelliis) HyalOSira Cl. (1822). — V. convex, thin, JV. complanata with eell-contents 

 lanceolate, rostrate or with rounded ends. L. 0,025 to 0,03; B. 0,oog6 ^ **""'" magnified. 



mm. Stria 29 in 0,oi mm. punctate. Frustule sliglitly siliceous, (juadrate. L. O.025; B. 0,oi 7 mm. 

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

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



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



K. Sv. Vet. Akad, Hutidl. Bd SG. N:o 2. 20 



