KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 27. N:0 3. 71 



Var. obtusa V. H. (1885). — V. lanceolate, with subrostrate, obtuse ends. L. 0,o5; B. 0,oi7 

 mm. Area lanceolate. — Syn. p. 97 Pl XI f. 8. 



Marine: Belgium (V. H.). 



Var. minor Grcn. (1880). — V. elliptic-lanceolate, with acute ends. L. 0,035 to 0,043; 

 B. 0,011 to 0,012 mm. Area lanceolate. Strise 10 to 11 in 0,oi mm. — A. D. p. 30 Pl. I f. 23. 

 V. H. S. p. 97 Pl. XI f. 11. Nav. minor Greg. D. of Cl. p. 477 Pl. IX f. 1 (1857)? 



Marine: Finmark! Belgium (V. H.). 



Var. Botteriana Grun. (1860). — V. broad, lanceolate, with slightly triundulate margin. 

 L. 0,07 to 0,08; B. 0,02 to 0,023 mm. Area large, lanceolate. Striee 8 in 0, 01 mm. (finely punetate, 

 Grun.). — Nav. Bott. Grun. Verh. 1860 p. 535 Pl. III f. 20. Nav. Esoculus Schum. P. D. p. 189 

 Pl. IX f. 53? 



Marine: Adriatic (Grun.). 



Forma minor Grun. — V. with rostrate ends and triundulate margins. L. 0,04; B. 0,oi36 

 mm. StriiB 12 in 0,oi mm. — 1. c. f. 10. 



Marine: Adriatic (Grun.). 



15. N. solida Cl. (1880). — V. elliptic-lanceolate, with subacute ends. L. 0,o58; B. 0,024 

 mm. Area rhombic-lanceolate. Strise 10 in 0,oi mm., the median alternately longer and shorter. 

 — A. D. p. 13 Pl. I f. 24. 



Marine: Finmark! 



16. N. mai-ginulata Cl. (1881). — V. rhomboid. L. 0,04 2; B. 0,oi2 mm Area very large. 

 StricE 17 in 0,oi mm. — N. E. D. p. 11 Pl. III f. 29. 



Marine: Pensacola, Florida! 



Pinnularia Ehb. (1843). 



Valve more or less elongated, usually linear, with rounded, obtuse, sometimes capitate, ends. 

 Median line straight or flexuose. Terminal fissnres generally large and distinct. Structure: appa- 

 rently more or less smooth, transverse stria;, usually radiate or divergent in the middle, convergent 

 at the ends. Connecting zone not complex. — The chromatophores form two plates, closely following 

 the interiör surface of the connecting zone. At the division of the cell they migrate from the 

 zone to the interiör surface of the välvas, and are then split up along the longitudinal axis of the 

 valve by fissures, simultaneously in the middle and at the ends (Pfitzer, Bau und Entw. p. 51). 

 — On conjugating, two parallel cells form two small egg-shaped auxospores, one above the other. 

 The auxospores are låter on developed into cylindrical transversely annulated bodies, bearing at 

 their eiids hemispherical caps (Pfitzer, Bau und Entw. p. 67). 



The following description of the structure of the valve is principally an abridged accoiint 

 of the researches of Pfitzer (Bau und Entw. p. 30), Flögel (J. R. M. S. ser. 2 IV p. 505) and 

 especiaUy Otto Muller (Ber. d. D. Bot. Ges. VII p. 169, 1889). 



The valve forms a more or less convex shell, and its median part a more or less narrow, 

 structureless area (the axial area) usually dilated in the middle to an irregularly rounded space, 

 or to a transverse fascia (the central area) and at the ends to a smaller space (the terminal area 

 or nodule). The axial area is bordered by strice, in most cases radiate in the middle and con- 

 vergent at the ends. In the middle of the centi^al area is the central nodule, and, connecting the 

 central and terminal nodules, the median line. 



The striä; are thinner parts of the valve and according to Pfitzer furrows on the outside, 

 according to Flögel and Muller channels on the inside, of the valve, closed, except in the middle, 



