98 p. T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



D. nitescens is remarkable for the week development of the central nodule, the horns of 

 which are scarcely distinct. In tliis respect it comes near to D. inscripta Cl. On corroded speci- 

 mens the alveoli are indistinct. 



72. D. daliuatica Grun. (18(50). — V. slightly constricted, with cuneate segments. L. 0,0.') 8 

 to 0,062; B. 0,014 to 0,01"; at the (lonstr. 0,oi2 to 0,oi4 mm. Central nodule small, rounded 

 elongated; its horns indistinct, close to the median line. Furrows narrow', not dilated in the middle, 

 crossed by faint costte. Costse 8 in 0,oi mm., alternating with double rows of alveoli. — Nar. 

 dalm. Grun. Verb. 1860 p. 525 PI. Ill f. 14. A. S. Atl. VIII f. 58, 59. N. Hornujii Pant. Ill 

 PI. XVI f. 241 (1893)? 



Marine: Morocco! Balearic Islands! Adriatic (Grun.), Bab el Mandeb! Macassar Straits! 

 Campeachy Bay! 



Var. Vidpecula A. S. (1875). — V. deeply constricted, with semilanceolate segments. L. 0,0(; a; 

 B. 0,017; at the constr. 0,oi2 mm. Central nodule small, its horns indistinct. Furrows linear, 

 moderately broad, near the horns with traces of the costai. Transverse costfe parallel, 8 in 0,oi mm., 

 alternating with indistinct (double?) rows of puncta. — Nav. Vulp. A. H. Atl. XII f. 5(5. 



Marine: Celebes (Atl.), Java! 



73. D. Mauleri Brun. (1880). — V. elliptical. L. 0,o37 to 0,o5; B. 0,oi3 to 0,oi5 mm. 

 Central nodule large, rounded; its horns indistinct, close to the median line. Furrows broad, for- 

 ming a narrow elliptical space, half as wide as the valve, with two rows of large puncta. Costaj 

 7 in 0,0 1 mm. alternating with double rows of alveoli, 10 in 0,oi mm. — Nav. Mauleri Brun. D. 

 des Ali)es p. 77 PI. I f. 18. D. especes n. p. 35 PI. XV f. 7. 



Lacustrine: Lac Leman! Sahara (Brun), Bottom-mud from Vettern! Of frequent occurrence 

 in the Baltic deposits of the Ancylus-epoch. 



Var. horiissica Cl. (1882). — L. 0,o2.'j to 0,o37; B. 0,oii to 0,oi2 mm. Costfe 7 to 8 in 

 0,0 1 mm. alternating, with (single?) rows of indistinct alveoli. — Nav. horiissica Cl. Phys. Oek. 

 Gesellsch. zu Konigsberg XXII p. 139. — A. S. Atl. VIII f. 17, 19. Nav. Mauleri Pant. Ill 

 PI. VII f 105; PI. IX f. 150. 



Slightly brackish water: Gulf of Bothnia at Nedre Kalix! Domblitton, Prussia fossil! 

 Rammer Moor (Atl.). 



74. D. Debyi Pant. (1886). — V. lanceolate, with obtuse ends. L. 0, i; B. 0,o3 mm. Cen- 

 tral nodule rounded quadrate; its horns slightly divergent in the middle, approximate. Furrows 

 very broad, with a row of strong puncta (reduced costte). Costte slightly radiate, 4 in 0,oi mm., 

 alternating with rows of alveoli. — Nav. Debyi Pant. I p. 23 PL XV f 136. 



Marine: Szakal, Hungary, fossil (Pant.). 



Var. eMiptica Cl. — V. narrow elliptical. L. 0, i; B. (),o3.) mm. Furrows broad. Costse 5 

 in 0,(11 mm. continued aci'oss the furrows and alternating with double rows of small alveoli. — 

 PI. II f. 4. 



Marine: Red Sea (Deby Coll.)! 



75. D. genunata Grev. (1859). — V. broad, linear, with rounded or cuneate ends and pa- 

 rallel or slightly concave margins. L. 0,o85 to 0,24; B. 0,o3 to O,ot;r> mm. Central nodule large, 

 (|uadrate; its horns parallel, closely approximate to the median line. Furrows broad, linear, tilling 

 a third or less of the surface of the valve. Cost;ti 3 to 6 in 0,oi mm., alternating with double 

 rows of twice as close alveoli. Along the horns of the central nodule is a row of short, but 

 strong co.stcB. 



Var. fos.silis Pant. (1886). — V. slightly constricted in the middle. L. 0, u; to 0,24; B. 0,04 5 

 to 0,o(ir) mm. Costa" 3 in 0,oi mm. — A. S. Atl. LXX f. 74. Nav. gemmata var. fossilis Pant. I 

 p. 25 PI. XX f 181. 



Marine, fossil: Hungary (P>eby Coll.)! Moravian Tegel! Moron (Atl.j. 



