130 p. T, OLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. - 



Var. lincata Cl. — L. of V. (),085; B. 0,015 mm. Striae 12 to 13 in 0,oi mm., composed of 

 puncta (about 9 in 0,oi mm.) forming straight, longitudinal rows. — A. lit or alis Gh. M. i). N:o 255. 



Marine: Mouth of Somme! 



Var. minor Grun. (1880). — Frustule elliptical, truncate. L. 0,o.3 to 0,037; B. 0,oi7 to 

 0,oi'.t mm. Divisions about 8 in 0,oi mm. Striii; 17 in O.oi mm. — A. D. p. 25. Cl. M. D. N:o 142. 



Marine: West coast of Sweden! 



Var. helgica Grun. (1880). — Frustule rectangular. L. 0,o33 to 0,o4 8; B. 0,o2i to 0,022 

 mm. Divisions of the zone about 9 in 0,oi mm. Stria" on the zone 18 in 0,oi mm. Valve with 

 1(5 to 17 finely punctate stri;e in (1, 01 mm. — V. H. Syn. p. 5(5 V. H. T. N:o 74. 



Marine: Belgium! 



1(). A. IjBvis Gheu. (1857). — Frustule hyaline and membranaceous, rectangular, with more 

 oi' less ti'uncate ends. L. (*,04 to O09; B. 0,oo to 0,04 mm. Zone with numerous divisions, (! to 

 9 in 0,01 mm. Stria", fine, about 22 in 0,oi mm. — D. of Clyde p. 514 PI. XII f. 74 «, h. r. 

 A. S. Atl. XXVI f. 10. Grun. A. D. p. 24 PI. I f. 8 (var of A. osfrcaria?). Dannf. D. of the 

 Baltic p. 20 PI. I f. 5. 



Brackish and marine: Finmark! North Sea! Balearic Islands! Java (A. S. Atl.). 



A. Irevis differs from ^4. ostrcaria by being more transparent and thin. The stria) are much 

 more delicate, and scarcely visible on the connecting zone. In some specimens the stauros is only 

 imperfectly developed, in which case A leevis offers a remarkable likeness to A. Imcolafa. Akin 

 to A. Icrvis is probably A. nobilis Flogel Pommerania Exp. p. 88 f. 9. 



Var. Icecissiiiia Greg. (1857). — F. very thin. L. 0,06 to 0,o7o; B. 0,023 mm. Divisions 

 of the zone ob.scure. Strife 27 to 28 in 0,oi mm. - A. IfPrissima Greg. I), of Clyde p. 513 PI XII 

 f. 72. A. S. Atl. XXVI f. 3, 13, 14. V. H. T. N:o 8. 



BrackLsh and marine: Sea of Kara! Finmark! Scotland! England! 



Var. wiiuifa Cl. — Frustule in L. about O.035; B. 0,02 mm. Stria- very delicate. — 

 A. Jcerissima H. L. Sm. T. N:o 615. 



Marine: Helgoland! 



Ya.v. x^rminida Grun. — Frustule in L. 0,oir) to O.ois; B. 0,oosr) mm. Stria' very delicate. 

 — A. hcriss. var. perniin. Grun. in V. H. T. N:o 9. A. hians PYogel? (Grun.). 



Marine: Swansea Docks, Schleswig (Grun.). 



To A. kevis .seems to belong A. excisa Greg. (D. of Clyde p. 521 PI. XIII f. 8(), 1857) and 

 A. S. Atl. XXXIX f. 3. 



17. A. qiiadrata Breb. (1889). — Frustule very tliin and membranaceous, rectangular, with 

 broad, truncate ends. L. 0,(i;); B. 0,03 mm. Stauros narrow. Zone witli numenms, strongly 

 marked divisions, about in 0,oi mm. Stria' exceedingly fine. - - KiJTZ Sp. Alg. p. 94? V. H. 

 Syn. p. 5() PI. I f. 24. A. parallcJa Flogel Pommerania Exp. p. 88 f. M (1.S73)? A. pohizo))(ita 

 Castr. D. of Challenger Exp. p. S PI. XXVII f. IS (1856)? 



Marine: Belgium (V. H.), Sweden, Fiskebackskil! 



This species is remarkable for its cell-contents, the chromatophores being numerous i-ounded 

 discs, as in the coccocliromatic diatoms. It differs from A. ostrcaria in its rectangular outline 

 and exceedingly fine stnustui'e. and from A. Ueris in its strongly marked divisions. 



Subgenus Amblyamphora. 



Frustule more or less rectangular. Connecting zone complex. Valves linear to lunate, with 

 obtuse, usually broad ends. Com])t)iU'nts of the median line divergent towards the dorsal margin. 

 Axial and central areas indistinct. Structure: fine puncta arranged in ti'aiisvcrse stria, which 

 on the ventral side usually divei'gc towai'ds the median line. No hnigitudinal lines. 



