- 1019 — 
D. Valvis linea et nodulo mediano praeditis. 
iC Frustula asyraraetrica, cinguloque recur- 
vo dorsiventrali, valvis dissimilibus : (una 
tantum lineam et nodolum medianum ha- 
bens. 
1. valvis rotundato-ellipticis. ... 14 Cocconeideae 
2. valvis oblongis 15 Achantheae 
m Frustula valvis similibus 
Cingulo valvisque asymmetricis . 16 Gomphonemeae 
1. Cingulo symmetrico, valvis asymme- 
tricis (dorsiventralibus) . . . . 17 Cymbelleae 
3. Cingulo valvisque symmetricis . . 18 Naviculeae 
SERIES II. Frustula latere aucta, axi infra- 
vulvari longitunalem aequanti vel saepius 
exsuperanti, cingulo plerumque lato et 
patenti sculptura praedito. 
a cingulo simplici haud tessellato 
1. Asymmetrica, cingulo inacquali, non 
evidenter sculpte, valvis latere et 
inaequaliter pro ratione productis 19 Hemiaulideae 
2. Symmetrica, cingulo lato, acquali, 
evidentius sculpte; valvis tumidis, 
prominentibus brevioribus instruc- 
tis 20 Bidulphieae 
h Frustula cingulo late extenso, parti- 
bus pluribus praetextis composito. 
1 Cingulo zonis perforatis perviis ob- 
texto, valvis naviculiformibus pro- 
ra inentiis carentibus .... 21 Strîatelleae 
2. Cingulo lamellulis minute sculptis, 
tessellato-cohaerentibus instructo ; 
vis calyptriformibus . , . . . 22 Rhizolenieae 
M. LANZI. 
