Familia I. NAVICULACEiE (Kuetz.) Heib. p. p. 



Naviculacece Kuetz. [1844] Bacill. p. 88 em. Heib. [1863] Dansk. Diat. p. 24; 



Grun. [1860] in Verh. Wien. Z. b. Ges. X. Band, p. 511 !, De-Toni [1890] Os- 



servaz Bacill. p. 895. 

 Amphipleuracece Grun. [1862] in Wien. Verh. XII, p. 320, Alg. Novara p. 6, 22. 



Valvse planse v. lenissime convexse, rhaphe recta v. incurva, typice 

 nodulo centrali singulo nodulisque terruinalibus 2 donatae*); latera 

 vaharum secus rhaphem rectam vel incurvam et secus axin trans- 

 versalem symmetrica. Latera connectivalia secus axin et longitudina- 

 lem et transversalem symmetrica **). Phaeophora laminaeformia (quan- 

 doque granuliformia), bina, medio zonas connectivales attingentia. 



Conspectus Generum 

 I. Frustula sine septis interioribus. 

 .4) Frustula solitaria, libere- vigentia (Navicuhce auct.). 



* Valvse rhaphem haud sigmoideam ostendentes (Cfr. Scoliopleuram). 



Navicula Bory. — Valva? nodulo centrali rotundato donatae, transverse pun- 

 ctato-striatse vel costatse; frustula e facie connectirali visa non achnan- 

 thoideo-arcuata nec longitrorsum plicata (incl. Pinnularia Ehr., Diploneis 

 Ehr., Stauroptera Ehr., Anomoeoneis et Neidium Pfltz.). 



Dictyoneis Cleve. — Valvae Naviculce, structura duplici: stratum interius 

 punctatum, exterius celluloso-reticulatum. 



Rhoiconeis Grun. — Est Navicula frustulis e facie connectivali visis achnan- 

 thoideo-arcuatis. 



Libellus Cleve — Est Navicula zona connectivali longitrorsum striato-plicata. 

 (Brachysira Kuetz.). 



Stauroneis Ehr. — Valvje ut in Navicuta, nodulo centrali transversiru dila- 

 tato, staurum efficiente, utroque fine haud bitido; striae haud decussata^. 



Pleurostauron Rabenh. — Est Stauroneis valvis in fasciam cohaerentibus (Ve- 

 risimillime Stauroneidis sectionem sistens). 



Schizostauron Grun. — Valva3 ut in Navicula sed nodulo centrali transver- 

 sim dilatato-lineari, utroque flne bifldo. 



Staurogramma Rabenh. — Est Stauroneis valvis striis decussatis instructis. 



*) Comparanda sunt geuera Jmphipleuram, Berkeleyam etc. Amphipleu- 

 ra (nodulo centrali nullo vel indistincto instructa) nodulos terminales valde 

 elongatos prsebet, Berkeleya vero nodulum eentralem deduplicatuni ostendit. 



**) Escipiunt ex. gr. genera Rhoiconeis, llhoicosigma quas frustula e fa- 

 cie connectivali achnanthilormi-arcuata ostendunt. Ab Achnanthaceis rece- 

 dunt valvis conformibus. 



