14 p. T. CLEVK, SYNOPSIS OF THE ^AVICULOID DIATOMS. " 



„, j Habitat: fresh- water N. gracilis Eiib. 



" ' \ — marine !)r). 



3 to 4 times longer tlian broad DG. 



, , 4 to G — — — — N. transitans Cl. 



■ ' G to 7 — — — — N. Zostercti Grun. 



10 - — — — N. directa W. Sm. 



„ . ( Valve rliomboidal N. siipcrba Cl. 



1 — lanceolate N. gelida Grun. 



( Striae between the margin and the axis faint 98. 



97. ] — unilaterally crossed by an area 99. 



I — crossed by undulating, blank bands 100. 



,,,, I Central nodule a short stauros N. finmarchica Cl. a. Grun. 



9b. ' •' 



J Centra 



( — — not stanroid N. transitans v. derasa (lY. kariana v. detersa). 



i Valv 



(If) ' Valve about 10 times longer than broad N. directa v. Incus. 



102. I 



104. {^^ 



5 to G — — — N. transitans v. incudiformis. ' 



j Valve very convex 101. 



1 — not — 102. 



j Valve fusiform N. vitriscalu Brun. 



\ — linear N. mediterranea Br. a. Cl. 



Valve linear with cuneate ends N. trigonocephala Cl. 



— lanceolate N. transitans v. erosa. 



j Lineation oblique iV. Kepesii Grun. 



I — straight 104. 



Valve narrow lanceolate N. ramosissima Ag. 



broadly — N. Kariana Grun. 



1. N. cryptocepliala KtiTz. (1844). — V. lanceolate, with rostrate-capitate ends. L. 0,025 

 to 0,035; B. 0,005 to 0,007 mm. Axial area indistinct. Central area small, somewhat transverse. 

 StriiB 16 to 18 in 0,oi mm., radiate in the middle, slightly convergent iu the ends, finely lineate. 

 — Bac. p. 95 PL III f. 26. Uonk. B. D. p. 37 PI. V f. 14. V. H. Syn. p. 84 PL VIII L 1, 5. 

 Nav. mutica Rabh. Alg. Sachs. N:o 965. 



Fresh water: Sweden! England! Belginm (V. H.), Germany! France! Arctic America! Green- 

 land! Argentina! Japan! 



Var. vcneta KtJTZ. (1844). — Smaller, with scarcely capitate ends. L. 0,025; B. 0,oo5 mm. 

 Strife 14 in 0,oi mm. — N. vencta KtJTZ. Bac. p. 95 PL XXX f. 76. Pedicino Ischia PL II f. 9 

 to 12? DoNK. B. D. p. 43 PL VI f. 13? iV^. crijpt. v. venefa V. H. Syn. p. 85 PL VIII f. 3, 4, 

 PL XIV f. 34. 



Brackish water: Sweden, Malmo! Venice (Klitz). 



Var. xuviuUa Grun. (1880). — V. rhombic-lanceolate. L. O,oit; to 0,023; B. 0,oog to 0,007 

 mm. Striffi about 15 in 0,oi mm. — V. H. Syn. PL VIII f. 6, 7, XIV f. 35. N. Rhomhulns 

 ScHUM. P. D. II N. p. 56, PL II f. 35 (1867)? N. Lanaffnla Schum. P. D. II N. PL II f. 34. 

 N. crijpfoc. V. Lancettida V. H. Syn. PL VIII f. 11. N.pumUa v. fossUts Pant. Ill PL V f. 75 (1893)? 



Brackisch water: Triest! 



Var. perminuta Grun. (1880). — V. lanceolate, not capitate. L. 0,oo8 toO,oii; B. 0,003 mm. 

 Striir, about 20 in 0,oi mm. — V. H. Syn. PL XIV f. 7. 



Var. cxilis KiJTZ (1844 p. p. accord, to Grunow). - V. lanceolate, with snbrostrate, obtuse 

 ends. L. 0,0 18 to 0,019; B. 0,oo5 mm. Striie about 19 in 0,oi mm. — V. H. Syn. p. 85 PL VIII f. 2, 4. 



Fresh water: Belgium (V. H.), Somme! Triest! 



2. N. gotljiiulica Grun. (1878). — V. narrow, lanceolate, with protracted, subacute ends. 

 L. 0,05 to 0,06; B. 0,008 mm. Axial area indistinct; central area small, orbicular. Strife 14 

 (middle) to 18 (ends) in 0,oi mm. radiate in the middle, convergent in the ends. — Cl. M. D. 

 N:o 161. V. H. Syn. PL VIII f. 8. 



Slightly brackish water: Sweden, (irothland! Tasmania! 



' N- irregularis P.\nt. N. superba v. elliptica. 



