138 1'. T. CLEVE, SYNOPSIS OF THE NAVIOULOin DIATOMS. 



name iV\ Pseudobacillum. The same form has been since figured in V. H. Syn. f. 9, but on tlie 

 same plate GtRDNOAV figures (f. 13) a smaller form as JV. Icfvissima Kutz. h\ this, somewhat obsoure 

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

 it may be a variety of N. FseudoltdcilhtM or of ^Y. lUtriUum or perhaps iY. snhhumHlaia. 



7. N. subhaniiilatii (Irux. (1S85). — V. linear, slightly gibbous in the middle, witli broad, 

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

 comma-like. Axial area indistinct, central very small. Stria; about 2()in(),oi mm. slightly radiate 

 throughout. Frustule with triundulated margins. — GrRUN. in V. H. Syn. p. lOb PI. XUl t. 14. 



Fresh water: Belgium (V. H.). 



Naviculse Decipientes (!run. (1880). 



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

 Axial and central areas small or indistinct. Tei'minal nodules not very thick. Central nodule 

 frequently transversely dilated. Strnctni'e: finely punctate stripe, 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. bncillares, which differ in the incrassate terminal 

 nodules, and also to A^ar. mirrosfif/maficrr. Some few forms are slightly asymmetrical and have 

 for this reason been considered as Cyijihelhf, Imt they are. no doubt, more closely allied to the 

 symmetrical forms of this section. On the other hand some CymJielIrr' (as C. cequalis) appear 

 to be related to species of this group. 



Artificial key. 



{ 



M 



. Valve acute N. rampJioides Pant. 



obtu.se 2. 



^ j Median line broad, flexuose i\". Semen Ehb. 



~ I — — straight, filiform 3. 



„ j Margins undulated 4. 



''■ I — not — 5. 



Valve lanceolate N. Integra W. Sm. 



— linear N. Lagersfedtii Cl. 



j Ends rostrate or cajntate 6. 



\ - not ~ - 9. 



,. I Median striae alternatelv longer and shorter N. injlafa Donk. 



b. < ■ 



1 — — not ~ — — — t. 



_ j Strife 20 or less in 0,oi mm 8. 



I — 30 or more — — iY. subtilissima Cl. 



I Strife radiate throughout N. Lundstromii Cl. 



1 — parallel at the ends N. jjrotrnctn Grun. 



„ j Linear-ellii)tical with broad ends N. seminoides Ol. 



1 Lanceolate — narrow — N. brasiliana Cl. 



(Valve lanceolate N. Crucicula "W. Sm. 



I — linear 11. 



Valve centrally gibbous N. gibbuln Cl. 



— not — " ~ 12. 



Median strife shortened N. subinjlafa Donk. 



— not — N. Kdlfvensis Grcn. 



"I 



12. 



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

 slightly rostrate, ends. L. O.o.^i to 0,09; B. 0,o23 to 0,029 mm. Median line fiexuose. Axial area 

 narrow, linear; central area snmll. orbicnlar. Strife in the middle 8 in Oju mm., of equal length. 



