KOXGL. SV. VET. AKADEMIENH IIAMJLIXGAR. BAND 26. X:(> 2. 179 



a iniilateral row of stigmas. (tRUNOW has formed for the species with stigmas the group Amjm- 

 mdrica, and for those without stigmas tlie group Stjiitntetrica, whicli names may in vievv of 

 maintainiiig the analogy with the Cymbellse be adventageously changed to Stigmatica and Asiig- 

 matica. 



There is a great resemblance between the cell-contents of Gomphonema and Cymbella, the 

 structure is the same in both genera, and they are no doubt nearly connected. We have in Cyni. 

 Beccarii Grun. a form, which is asymmetrical to the transverse axis, and, there are several other 

 Cymbelloid varieties of Gomphonema. Gomph. Cymbdla Brun may be considered as an inter- 

 mediate link between the two genera. 



The outline of the forms of Gomphonema is very variable, and older anthors have paid too 

 much attention to it in forming new species. There exist iu the same species all possible transi- 

 tions, from purely clavate, to strongly biconstricted forms, so that outline only cannot be regarded 

 as a good specific distinction. 



Most species of Gomphonema inhabit fresh water, some brackish water, and there are also 

 purely marine forms, the latter being all astigmatical. They are usually attached by dichotomously 

 branched gelatinous stalks to algte, stones, leaves of water-plants etc. Some forms are inbedded 

 in gelatinous masses, but frustules of attached specie.s occur also occasionally free. 



Artificiell Iceij. 



I. Stigmatica. 



j Median striae alteruately longer and sliorter 2. 



t — — not — — — 3. 



„ I L. 0,1 to 0,12 mm G. geniinatmn Lyngb. 



\ L. 0,0.5 mm G. constrictum Eblb. 



) Axial area distinct or bi'oad 4. 



' 1 - — indistinct or narrow 7. 



, ) .4rea linear 5. 



\ — lanfeolate 6. 



) Ends subacute or apiculate G. validum Cl.. 



'1 — broadly truncale G. Berggrenii Cl. 



I Strise aboixt 12 in 0,1 mm G. ventricoisum Geeg. 



I — — 8 — G. oxycephahim Cl. 



_ I Central area transverse 8. 



I — — small and rounded or indistinct 12. 



) Central area unilateral 9. 



■ i — — bilateral 10. 



I Ends apiculate G. Augur Ehb. 



9. ■! — rostrate to truncate G. angiistattim Kiiiz. 



\ — broad, rounded-truncate G. subtile Ehb. 



.., j Central area narrow G. gracile. Ehb. 



I — — broad 11. 



I StriiB coarsely punctate G. semiape.rhim Grun. 



1 — obscnrely — G. intricahim KiJTZ. 



^y I Valve biconstricted G. acuminatum Ehb. (G. subchivaUim var. Mn.sMa). 



'■ 1 — not — 13. 



I Ends capitate G. sphcerophorwn Ehb. 



13. ■! — apiculate G. apicatum Ehb. 



I — rounded 14. 



... j StrisB coarsely punctate G. lanceolatmn Ehb. ■ 



\ — flnely or obscnrely — Ib. 



' G. cantalicum Br. a. Hérib. 



