22 



P. T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



accad dei ii. Lincei 1873 p. 406 Pl. VII f. 2. Peragallo Villefranche D. p. 42 Pl. II f. ]X. A. Szon- 

 tacjlni Pant. III Pl. VII f. 104 (1893). 



Marine: Marocco! Balearic Islands! Adriatic! 



To the genus Auricida may belong Aur. Grunoivii Pant. III Pl. XXXI f. 453. Annjhiprora 

 striata Pant. III Pl. XXXIX f. 543 and Amphiprora FetJiöi Pant. III Pl. XLI f. öOö all un- 

 known to me. 



I 



^S;: 



M 



Tropidoneis Cl. (1891). 



Valve elongated, lanceolate, more or less convex and acute, frequently with a wing. or 

 longitiidinal band, on one or both sides. Median line straiglit, on a central, or excentric, keel; 

 its central pores approximate. Axial area indistinct. Central area small, roiinded, or transversely 

 dilated. Structiire, iine pimcta, forming transverse, not radiate, striai, and longitudinal, more or 

 less straiglit, miich finer, strife. Connecting zone not complex. 



Cell-contenfs. Tlie cell of T. vitrea contains two chro- 

 matophore-plates along the connecting zone, they foUow the in- 

 teriör of the larger side of the valve; and send some divisions 

 into the keel (Pfitzer: Bau nnd Entw., p. 93). 



The plates of T. elegans are similar, but thej' have 

 three deep constrictions nearly dividing them into almost equal 

 patches, the margins of which are deeply indented. T. Lepidop- 

 tera has also two stronglj' indented or serrated plates along the 

 connecting zone. At the ends of the frustule are uumerous small 

 grannles in lively motion. T. conserta has an entireh' different 

 arrangement of the cellcontents, so tliat it seems qnestionable 

 whetJier this species shovild not be placed in Auricula, the di- 

 visions of the zone being perhaps too delicate to be visible. 

 T. conserta has along the neutral side of the zone a flat plasma- 

 mass including two chromatophore-plates separated by a narrow, 

 oblique fissure. The plasma-mass has a broad sinus at each end. 

 The first known species of this genus is Amphiprora 

 vitrea, named 1853 by W. Smith. Other forms have since then 

 been described by Gkegory, Greville and others as Amphip)rora, 

 including both forms with sigmoid median line and complex zone, 

 and with straight median line and not complex zone. Rabenhorst 

 1864 proposed (Fl. Eur. Alg. p. 257) for the former the generic name 

 Amphicawpa (låter on changed by Pfitzer and Griwow to Ainphi- 

 tropif) and retained the genus Amphiprora for the latter. As, 

 however, the first species of Amphiprora (.4. alaia KfTz). so de- 

 scribed as to be distinctly recognized, belongs to the group with 

 sigmoid median line, it seems to me that that name, rather than 

 Amphicampa, should be retained for this group. In 1871 Pfitzer 

 created the genus Flagiotropis, and family Fhuiiotropiclce, for forms 

 with straight, excentric, keels Ijäng diagonally in opposite direc- 

 tions, represented by P. hultica Pfitz. whicli is very probably the same as Amphiprora rit rea AV. Sm. 

 For forms with excentric keels lying in parallel directions Grunow 1880 (Van Heurck"s S^^n. 

 Pl. XXII bis.) created the genus (or more coi-rectly subgenus of Amphora) Amphoropsis, in which 

 he includes both forms with complex, and not complex, zones. In the year 1891 I (Diatomiste 

 I p. 51) proposed to unite in one genus, Tropidoneis, the forms of Amphiprora with straight 

 median line, those of Plagiotropis, and of Amphoropsis with non-complex zone. 



ly 



Tropidoneis elegans, TiOO times magnilieJ. 



