KONGL. SV\ VET. A K ADKiMl KNS II A .\ I )L1 N (JA K. HAM) 26. N:() 2. 171) 



a unilateral row of stigmas. (TtKUNow has t'ormcd tor the species with stigmas the gntuj) Asi/ni- 

 jitcfricd, and for those without stigmas the group Si/iiiDicfrird, which names may in view of 

 maintaining the analogy with the Cymhelhe be adventagcously changed to St/fpiiiil/cK and Asfuj- 

 ■tnatica. 



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 Cytii. 

 Bcccdrli (tRUN. a form, which is asymmetrical to the transverse axis, and, thei'o are several other 

 C'ymbelloid varieties of (Tomphonema. Gompk. Cymbella Brfn may be considered as an inter- 

 mediate link between the two genera. 



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

 much attention to it in forming new species. There exist in 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 friistules of attached species occur also occasionally free. 



Artificial hey. 



I. Stigmatica. 



j Median strisB alternately longer and shorter 2. 



1 — — not — — — 3. 



) h. 0,1 to 0,12 mm G. geminatnm Lyngb. 



\ L. 0,115 mm G. constridnm Ehb. 



., I Axial area distinct or broad 4. 



I — -- indistinct or narrow 7. 



. ( .\rea linear 5. 



1 — lanceolate 6. 



j Ends subacute or ajjiculate G. validuni Ci,.. 



\ — broadly truncate G. Berggrenii Cl. 



. J StricE about 12 in 0,1 mm G. vcntricosuni Greg. 



I — — ''^ — G. oxycephnlum Cl. 



I Central area transverse 8. 



1 — — small and rounded or indistinct 12. 



^ J Central area unilateral 9. 



■ I — — bilateral 10. 



j Ends ai)iculate G. Augur Ehb. 



9. , — rostrate to truncate G. angustatum Kutz. 



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



Central area narrow G. qrarile Ehb. 



— — broad 11. 



10. 



j Stri* coarsely punctate G. semiapcrtum Grun. 



I — obscurely — G. intricntvm KtiTZ. 



,^ I Valve biconstricted G. acumiiiaftim Ehb. (G. Huhdavntum var. Miistela). 



\ — not — 13. 



j Ends capitate G. sphcerophorum Ehb. 



13. . — apiculate G. apicatuni Ehb. 



I — rounded 14. 



^ , J Stria; coarsely jiunctate G. lanccolatum Ehb. 



\ — finely or obscurely — If). 



' G. cantalicum Br. a. Herib. 



