138 



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



name N. Pseudobacillum. The same form has been since figured in V. H. Syn. f. 9, but on the 

 same plate GtRUNow figures (f. 13) a smaller form as N. Icevissima KiJTZ. In this, somewhat obscure 

 figure, the lateral extensions of the terminal nodules are not visible, and it seems uncertain whether 

 it may be a variety of N. Pseudobacillum or of N. JSacillum or perhaps N. subhamulafa. 



7. N. subliainulata G-run. (1885). — V. linear, slightly gibbons in the middle, with broad, 

 rounded ends. L. 0,02; B. 0,oo5 mm. Terminal nodules not laterally extended. Terminal fissures 

 comma-like. Axial area indistinct, central very small. Striae about 26inO,oi mm. slightly radiate 

 throughout. Frustule with triundulated margins. — GtEUN. in V. H. Syn. p. 106 PI. XIII f. 14. 



rre,sh water: Belgium (V. H.). 



Naviculse Decipientes Grun. (1880). 



Valve lanceolate to linear, with subacute to truncate, frequently rostrate or capitate, ends. 

 Axial and central areas small or indistinct. Terminal nodules not very thick. Central nodule 

 frequently transversely dilated. Structure: finely punctate striae, slightly radiate or almost pa- 

 rallel, more distant in the middle, than at the ends. Connecting zone not complex. 



This group is nearly akin to the Nar. bacillares, which differ in the incrassate terminal 

 nodules, and also to Nav. microstigmaticce. Some few forms are slightly asymmetrical and have 

 for this reason been considered as CymheUcp, but they are, no doubt, more closely allied to the 

 symmetrical forms of this section. On the other hand some Cymbellw (as C. cequaJis) appear 

 to be related to species of this group. 



Artificial hey 



{Valve acute 

 — obtuse . . 

 J Median line broad, ilexuose . . 

 \ — — straight, filiform . 



j Margins undulated 



\ — not — 

 ( Valve lanceolate . . 



n 



— linear . . 



Ends rostrate or capitate . 



— not — — 



„ J Median striae alternately longer and shorter 

 ' \ — — not — ■ — — — 



7 



8. 



9. 



10. 



{Striae 20 or less in 0,01 mm. . . . 

 — 30 or more — — 

 I Striae radiate throughout 

 \ — parallel at the ends .... 



Linear-elliptical with broad ends . 

 Lanceolate — narrow — 



\Val\e lanceolate ... ... 



linear . 



I: 

 ■ I' ~ 



■{ 



_ ^ I Valve centrally gibbous 

 \ — not — 

 Median striae shortened 

 — — not — 



N. ramphoides Pant. 

 . . . . 2. 

 . . . N. Semen Ehb. 

 . 3. 

 4. 



5. 



. . N. integra W. Sm. 

 N. Lagerstedtii Cl. 

 . 6. 



9. 



. . N. inflata Donk. 

 7. 



N. subtilissima Cl. 



N. Lundstromii Cl. 



N. protracta Geun. 



, . N. seminoides Cl. 



N. brasiliana Cl. 



N. Crucicula W. Sm. 



11. 



. . N. gibbula Cl. 



12. 



N. subinflata Donk. 

 N. Kdlfvensis Gkun. 



1. N. Semen Ehb. (1843). — V. elliptic-lanceolate, with broad, almost truncate, frequently 

 slightly rostrate, ends. L. 0,o5 to 0,09; B. 0,023 to 0,029 mm. Median line flexuose. Axial area 

 narrow, linear; central area small, orbicular. Striae in the middle 8 in 0,oi mm., of equal length. 



