KONOL. SV. VKT. AKADEMIENS IIANDLINGAH. HAND 27. N:(» 3. 71 



Var. obtusa V. H. (1885). - V. lanceolate, with suhrostrate, obtuse ends. L. (),or, ; H. (»,i)i7 

 mm. Area lanceolate. — t^yn- p- 97 PI XT f. 8. 



Marine: Belgium (V. H.). 



Var. minor Grun. (1880). — V. elliptic-lanceolate, with acute ends. \j. O.d.ir. to (),t)4.t; 

 B. 0,0 11 to 0,012 mm. Area lanceolate. Striit; 10 to 11 in 0,oi mm. — A. I). ]). IM* PI. I f. 28. 

 V. H. S. p. 97 PL XI f. 11. Nav. minor Gre(j. D. of CI. p. 477 PI. TX f. 1 (18:,7)';' 



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



Var. Botteriana (tRUN. (18(j0). — V. broad, lanceolate, with slightly ti'iundnlate mai'gin. 

 L. 0,u7 to 0,08; B. 0,02 to 0,023 mm. Area large, lanceolate. Strite 8 in 0,oi mm. (tinely punctate, 

 Grun.). — Nav. Bott. Grun. Verh. 18(50 p. 535 PI. Ill f. 20. Nav. Esoruhis Schum. R D. p. 189 

 PI. IX f. 53:' 



Marine: Adriatic (Grun.). 



Forma minor Grun. — V. with rostrate ends and triundulate margins. L. 0,04; B. (),oi,i6 

 mm. Strifce 12 in 0,oi mm. — 1. 0. f. 10. 



Marine: Adriatic (Grun.). 



15. N. SOlida Cl. (1880). — V. elliptic-lanceolate, with subacute ends. L. 0,of,8; B. 0,024 

 mm. Area rhombic-lanceolate. Stria; 10 in 0,oi mm., the median altei'iiately longer and shorter. 

 — A. D. p. 13 PL I f. 24. 



Marine: Finmark! 



Ifi. N. marginulata Cl. (1881). — V. rhomboid. Ti. 0,042; B. 0,012 mm Area very large. 

 Stricfc 17 in 0,oi mm. — N. R. 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 ilexuose. Terminal fissures generally large and distinct. Structure: appa- 

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

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

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

 zone to the interior surface of the valves, 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 later on developed into cylindrical transversely annulated bodies, bearing at 

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



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

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

 especially 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 central area is the central nodule, and, connecting the 

 central and terminal nodules, the median line. 



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

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



