i6à 
C - valvae strìis pseudoraphe ìnterruptìs, pseudonodulis et intervallo 
hyalino transverso carentes, interdum apicibus vestigio raphes 
brevis ad instar illius Amphipleurarum notatae 
Dimeregramma Ralfs 
D - valvae pseudoraphe et pseudonodulo parvulo notatae 
Glyphodesmis Grev. 
E - valvae pseudoraphe et pseudonodulo magno notatae 
Omphalopsis Grev. 
Eunotieae. 
A - Valvae nodulis apicalibus carentes Pseudoeunotia Grun. 
B - valvae nodulis apicalibus praeditae 
a uniformiter striatae Eunotia Ehr. 
b striatae sed margine convexo granulis majoribus aut spinulis or- 
natae Actinella Lewis 
Epithemieae. 
A - Valvae apicibus rotundatis vel capitulatis sensim vel non atte- 
nuati, raphe aegre conspicua Epithemia Breb. 
B - valvae apicibus attenuatis; raphe bene conspicua, nodulo cen- 
trali instructa Rhopalodia O. Muli. 
Nitzschieae. 
A - Frustula intra vaginas mucosas inclusa Homoeocladia A g. 
B - frustula libera, carinae (raphe) in una alterave valva per diame- 
trum oppositae Nit\schia Hass. 
C - frustula libera, carinae (raphe) secus latus unum frustuli vergen- 
tes Hant^schìa Grun. 
Surirelleae. 
A - Valvae transverse undulatae, undulationibus e latere conspicuis, 
raphe recta Cymatopleura W. Sm. 
B - valvae ellipticae, saepe medio constrictae, raphe cruciata, apici- 
bus bifurcata Hydro Silicon Brun 
C - valvae complanatae, cuneatae, costatae et alternatim granulatae, 
raphe recta Podocystis Kuetz. 
