KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 26. N:0 2. 



1. Nitzchies 



2. Ampliiprora 



3. Plenrosigma 



4. Tropidoneis 



5. Naviculffi fu- 

 siformes 



6. Frustulia 



7. Naviculfe mi- 

 crostigmaticffi 



8. Navicnlae de- 

 cipientes 



Ampliiprora (2) Aurieula. 



Tropidoneis (4). 



. . . . Dictyoneis .... Mastoneis. 



. . . . Scoliotropis .... Gomphoneis. 



. . . . Pleurosigma (3), Toxonidea. 



. . . . Naviculae Decussate . . . Anomoeoneiä 



Naviculae fusiformes (5). 



Naviculse microstigmaticEe (7). 



Naviculse otliosticliae. 



Gyrosigma. 



Frustulia (6). 



Cistula. 



Stenoneis. 



Ampliipleura. 



Brébissonia. 



Nav. minusculcE .... Microneis. 



Nav. decipientes (Ö). 



Nev. punctatse (9). 



Anorthoueis. 



Eucocconeis. 



Halaniphora. 



Oxyamphora. 



Amblyamphora. 



Psammampliora. 



Nav. bacillares. 



Nav. entoleiEB. 



Nav. mesoleis. 



.... Heteroneis. 



y. Naviculie 

 punctatae 



10. Naviculse li- 



neolatse 



11. Naviculse Ise- 



vistriatiE 



12. Naviculae ly- 



ratae 



13. Diploneis 



14. Pseudo-am- 



phiprora 



15. 



IG. Mastogloia 



Nav. lineolatffi (10). 



Nav. lyrata; (12). 



Nav. heterostichae .... Actinoneis. 



. . . . Aclinanthidium. 



. . . . Disconeis. 



Cymbella. 



Gomplionenia, Rhoicosphenia. 



Trachyneis. 



Nav. lEevistriatse (11). 



Pinnularia. 



G\'mbaiuphora. 



Archsamphora. 



Diploneis (13). 



Pseudo-amphiprora (14). 



Amphora .... Diplamiihora. 



Cymatoneis. 



Scoliopleura. 



Nav. nicobaricae. 



Nav. luxuriosEe. 



Caloneis .... Neidium. 



.... Calampbora. 



.... Aehnantlies 

 I . . . . Mastogloia. 

 I Cocconeis. 

 [ Camp3'loneis. 



Plenroneis. 



Tropidoneis comprises botli symmetrical not-winged and asymmetrical winged forras. The 

 former appear to be related to i\i& NaviculcB microstigmaticce &nå Nav. fnsiformes. As asymmetrical 

 forms of the Nav. microstigmaticce are to be considered tlie following sections of the old genus Amphora: 

 Oxi/ampJiora, Amhlyampliora, PsammavipJwra probably also Halamplwra. Anorthoneis is probably 

 an asymmetrical form of Nar. microsiigmaticce. The Nav. minusculce, of wliich Microneis and 

 Eucocconeis appear to comprise degenerating forms, are probably also allies of Nav. microstigmaticce _ 

 To the last named large section the Nav. decipientes, Nav. e.ntoleice and Nav. mesoleice are certainly 

 akin. Heteroneis may comprise degenerating forms allied to the same group. 



From tlie Nar. microstigmaticce the passage is gi-adual to the Nav. punetatte and Nav. hcterostichce 

 and the former section is very closely connected with the Nav. lyratcB. As degenerating forms are 

 perhaps to be regardcd Disconeis and AchnantUidium. Also some asymmetrical forms exist in 

 the .section Nav. punctatce. Some Cymhellce rejDresent very likely asymmetrical forms of Nar. 

 punctatce. 



The Naricidce Lyratce are by intermediate forms connected with Diploneis. Akin to the 

 Nav. lyratcB I also consider Pseudo-ampJiiprora. The new groups Amphora and Diplam.phora, 

 bi'oken out from the old genns Amphora., may be regarded as asymmetrical forms of Diploneis. 



Pseudo-amp)hiprora is connected by intermediate forms witli Caloneis, to which also Neidium 

 seems to be allied. 



The Nav. lineolatce pass över to tlie gronp Punctatce by transitional forms, and the former 

 are also akin to Trachyneis (with the asymmetrical form Amphora Clevei). A part of the Cymhellce, 

 Gomphonema, PJioicosphenia and Amphora lahuensis may be considered as asymmetrical forms of 

 the Nav. lineolatce. Degenerated forms of the Nav. lineolatce are probably to be fonnd in Actinoneis. 

 ■"— On the other hand the Nav. lineolatce are closely connected Avith the Nar. Icevistricdce, and those 

 with Pinnularia, and I consider, with much hesitation, Cymiamphora as asymmetrical forms of the 

 Nav. Icevistriatce. 



Kongl. Sv. Vet. Akad. HaDdl. Band 2G. N:o 2. 2 



