— 897 — 
Rhoicosigma Grun. — Frustula achnanthiformia, rhaphe sigma- 
toidea. 
Toxonidea Doiik. — • Fruslula levitcr torta, latere arcuata, zona 
connectivali diagonali-percursa, valvae lateribiis non symme- 
tricis, striatae, rhaphe arcuata. 
Donkinia Pritch. — Frustula a latere medio constricta panduri- 
formia, zona connectivali recta ; valvae linearcs, rhaphe sig- 
matoidea, abrupte ecentrico, marginem attingente (Genus ad 
Amphiproraceas vergens). 
B) Frustula intra massam mucosam vel tubos mucosos, subinde 
figuralos nidulantia (Schzzonemeae auct.). 
* (Sine stratu interiori costarum). 
t Gen. aquae dulcis. 
Colletoiiema (Bréb.) H. V. H. — Valvae structura paullo excen- 
trica donatae, nodulis terminahbus ab apice valvarum remo- 
lis striisque radiantibus discretis. Frustula tubis mucosis in- 
clusa. 
Frustulia Ehr. — Ex Grunow sislit saltem ex parte Naviculae 
species. Ex Gleve in litt. idem ac Vanheurckia Bréb. 
tt Genera marina. 
Schizonetna Ag. — Gharacteres Golletonematis sed tubulis muco- 
sis figuratis algasque majores simulanlibus (incl. Phlyctaenia 
Kuetz. et Micromega Kuetz.). 
Dickieia Berk. — Gharacteres Schizonematis sed massis mucosis 
foliaceis ulvaeformibus. 
C) Frustula stipite mucoso suffulta 
Genus Brebissonia Grun. (Inter Amphipleuraceas disposui). 
D) Genera mihi parum cognita vel dubia. 
Porostauros Ehr. — Genus Naviculaceis adscriptum, mihi adhuc 
plane ignotum. 
Libellus Gleve. — Genus a Schizonemate vix sejungendum. 
E) Genera delenda. 
Perizonium G. et J. — Statum sporangialem Naviculae sistens. 
Craticula Grun. — Slalum abnormen sistens (incl. Stictodes- 
mis Grun.). 
11. — Stratus internus costarum praesens {Mastogloiaceae 
auct.). 
Mastogloia Thw. (incl. Stigmaphora Wall.) — Frustula solitaria 
