18 Acta Societatis pro Fauna et Flora fennica, VIII, n. 2. 



natural genus. Nearly related to some forms of Aehnanthes are 

 Coeconeis and Orthoneis and to the latter Mastogloia. 



The natural system of the diatoms with a median line (Ra- 

 phidese) seems, then, to be represented by the following arrangement 



ht* i- ^ t.7 • j. • i Amphoropsis — Amphora p. p. 



(Xitzsclna) - Plagwtropis > Am |, hipr £ ra _ Reurosigma - Navicula (Vega^ CI.) 



Nav. radiosae. 

 (see below). 



Pinnularia — ? — N. limosre (?) 

 Schizonema (raraosissimum-group.) 

 Punctata? (see below). 

 Nav. rad™«{ Rhoiconeis (R. Bolleana). 



Trachyneis (Nav. velata, N. pulchella, Alloioneis Kurzn. AL 

 antillarum). 



I 



(? Group of N. triundulata — ? Diploneis — '? — Amphora p. p. 

 r i n / Gomphonema. 

 i\av. punciuuc, ^ muella \ Amphora p. p. 

 I Lyrse. 

 ( Decipientes (see below). 



(Stauroneis, Amphora p. p. 

 Rhoiconeis (R. Garkeana). 

 Scoliopleura (S. tumida). 

 a u,v. u,*™ ¥ ™>™> , / ? Am phiprora. 



ComplexaeJ Schizonema (comoides-group). 



(Ampt 



lora p. p. 



Qaadriseriatse p. p. 



T ■ ( ? Pinnularia. 



Limosai' , Xeidium 



Nav. formosa t ? Palpe brales. 



?Nav. Schneideri — Scoliopleura p. p. 



? Amphora p. p. (A. Grevilleana). 



( Amphipleura, Berkeleya. 

 Frustulial Brebissonia. 



( ? Anomo3oneis. 



Orthoneis, Mastogloia. 



r, • I Aehnanthes. 



Coeconeis Campyloneis . 



I Rhoicosphenia 



I have in the above exposed my views about the arrange- 

 ment of the naviculoid diatoms, but I must confess that I am not 

 at the moment prepared to propose it as a definite system. There 



