Naviculse Minusculse Cl. 



Valve small, broadly lanceolate to elliptical, slightly silicious. Areas indistinct. Structure 

 slightly radiate, very fine or indistinct striee. Connecting zone not complex. 



The species of this group are usually of extremely small size, and live in fresh or salt water. 



Artificial hey. 



^ j Marine species 



I Fresh-water species .... 

 „ I Valve elliptical . . 



I — lanceolate . . 



/ Striffl coarse (17 in 0,oi mm.) 



\ — fine (30 and more in 0,oi mm.) 



( Valve elliptical 



H 



lanceolate . . 

 Striae indistinct ... 

 — about 30 in 0,oi mm. 



/ Striae radiate 



parallel . . 



{Valve broadly elliptical 

 — narrow . . . 



Valve broadly lanceolate 

 — narrow — 



M 



. . 2. 

 . 3. 

 N. dehilissima Gsun. 

 . N. bahusiensis Gbun. 

 . N. lucidula Gbun. 



4. 

 . ... 5. 



8. 



N. pelliculosa Br:^b. 



6. 



. N. atomus Naegeli. 



7. 



. ■ . N. muralis Grun. 



N. exilissima Gkun. 



N- minuscwla Gkun. 



N. microcephala Grun. 



1. N. pelliculosa (Br^b.) Hilse (1862). — V. very slightly silicious, elliptical, v^ith broad 

 and rounded ends. L. 0,oo9; B. 0,oo4 to 0,oo5 mm. Strise extremely fine. — Frustulia pellic. 

 Br^b. (according to Grunow). Frustulia sp. Gkun. Verb. 1860 p. 573 PI. VII f. 18. Nav. pell. 

 HiLSB Eabh. a. E. N:o 1265. V. H. Syn. PI. XIV f. 32. 



Fresh water: Germany (A. E.), France (Brfeb.). 



2. N. debilissiraa Grun. (1884), — V. elliptic-lanceolate L. 0,007; B. 0,oo5 mm. Strise 

 not seen. - Franz Jos. Land D. p. 104 (52) PI. If. 42. 



Marine: Franz Josefs Land. 



3. N. muralis Grun. (1880). — V. elliptical, with rounded ends. L. 0,oo6 to 0,012; B. 0,oo4 

 mm. Areas indistinct. Striae very slightly radiate, about 30 in 0,oi mm. — V. H. Syn. PL XIV 

 f. 26 to 28. N. Atomus Schum. P. I). I Nachtr. p. 21 f. 24? 



Fresh water. 



4. N. exilissima Grun. (1880). — V. linear-elliptical. ■ L; 0,oo5 to 0,oi; B. 0,oo3 mm. 

 Areas indistinct. Striae about 40 in 0,oi mm., almost parallel; the median more distant. — V. H. 

 Syn. p. 108 PL XIV f. 30. 



Fresh water: Belgium (V. H.). 



