138 P. T. OLEVE, SYNOPSIS f)F THE NAVICULOID DIATOMS. 



name JV. Pseuclobacillum. The same form lias been since figured in V. H. Syn. f. 9, bnt on the 

 same plate Grunow fignres (f. 13) a smaller form as iV. laprissinia Kutz. In this, somewhat obscure 

 figure, the lateral extensions of the terminal nodnles are not visible, and it .eeems uncertain -nhether 

 it niay be a variety of iV. FseitdohariUuni or of N. BariUnni or perhaps K. suhhamuhtfu. 



7. N. 8iil)]iaiinilata Grun. (1885). — V. linear, slightly gibbons in the middle, with broad, 

 ronnded ends. L. 0,o-2; B. 0,005 mm. Terminal nodnles not latei-ally extended. Terminal fi.^snres 

 conima-like. Axial area indistinet, central very small. Strite abont 2(JinO,oi mm. sliglitly radiate 

 throughout. Frustnle with triundnlated margins. — GrRUN. in V. H. 8yn. p. lOli PI XIII f. 14. 



Fresh water: Belginm (Y. H.). 



Naviculse Decipientes (iiuN. (IS80). 



Valve lanceolate to linear, ^^-ith snbacnte to trnneate, freqnently rostrate or capitate, ends. 

 Axial and central areas small or indistinet. Terminal nodnles not verv thick. Central nodule 

 frequentlj' transversely dilated. Strnctni^e: finelj' pnnctate striw. slightly radiate or almost pa- 

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



This gronp is nearly akin to the Xar. baeillares, which dilFer in the incrassate terminal 

 nodnles, and also to Xar. m/crosfif/maficrc. Some few forms are sliglitlj' asj^mmetrical and have 

 for this reason been considered as Cymbellrp, bnt they are, no donbt, more elosely allied to the 

 symmetrical forms of tliis section. On the nther liand some CymhcUrr' (as C. (Pqnalis) appear 

 to be related to species of this gronp. 



Artificial l-e.y. 



. I Valve acute K. rampltoides Pant. 



I — obtiise 2. 



g J Median line broad, flexnose X. Senien Ehb. 



~ \ — — straiglit.. flliform .9. 



„ j Margins nndulated 4. 



1 — not — 5. 



. J Valve lanceolate K. integra "W. Sjr. 



\ — linear iY. Lagersfedtii Cl. 



i. j Ends rostrate or capitate 6. 



"'' i — not — — 9. 



„ I Median strite alternately longer and sliorter K. injiata Donk. 



' \ — — not — — — — 7. 



I Strife 20 or less in 0,0 1 mm 8. 



i . ■ 



\ — 30 or more — — N. subtilissima Cl. 



„ ) Stri» radiate throughout X. Lundströmii Cl. 



\ — parallel at the ends K. protracfa Grun. 



Q J Linear-elliptical with broad ends X. seminoides Cl. 



\ Lanceolate — narrow — N. brasiliana Cl. 



j„ (Valve lanceolate N. Cnirictda "W. S>r, 



I — linear 11. 



.. J Valve centrally gibbous X. gibbula Cl. 



■ \ — not — — 12. 



..g J Median stria; shortened X. xiihiiijlnfn Donk. 



"' 1 — — not — X. Eälfvensis Grcx. 



1. N. Semeii Etib. (1843). — V. elliptic-lanceolate, with broad, almost trnneate. freqnently 

 slightly rostrate, ends. L. 0,05 to 0, 09; B. 0,o23 to 0,o29 mm. .Median line flexnose. Axial area 

 narrow, linear; central area small, orbicnlar. Strite in the middle 8 in (l.m mm., of eqnal length, 



