— 906 — 
Fragilaria Lyngb. — Valvae symmetricae, ecostatae, polis confor- 
mibus ; fruslula rectangularia, in fascias calenasve conjuncta. 
Grammonema Ag. - Est Fragilaria frustulis iinperfecte siliceis 
(An satis distinctum genus ?). 
Clavicula Pant. — Frustiila elongata, po'is incrassatis, valvae dna; 
bus areis levibus longitudinalibus percursae. 
Cymatosira Grun. — Frus'ula e zona connoclivali visa undulalo- 
arcuata ; valvae lanceolatae, grosse punclatae (Huic generi affi- 
ne videlur, teste Gleve, genus Rutilaria Grev.). 
Rhaphoneis Ehr. p.p. — Frustula quadrangula, simplicia, navicula- 
ria, fronte late lanccol. v. ovata, striis vel costis transversis 
(ubi adsunt) vitta vel area longitud. interruptis. 
Obs. Species costis in valvis praebentes secernendae. 
Doryphora Kuetz. — Est Rhaphoneis^ valvis stipitalis {Rhapho- 
neidi ut subgenus includendum). 
Fam. Plagio grammaceae P. Petit 
Petit (1889) in Peli. Diat. II, 1, p. 80. 
Valvae ellipticae, plus minus elongatae, granulis inargaritaceis tran- 
sverse longitudinaliterque ordinatis ornatae, apicibns levibus (ocelbs seu 
pseudonodulis) medio area levi v. stauro vel pseudonodulo instructae ; 
pseudorhapbis saepe pranseus ; frustula zona connectivali visa rectan- 
gularia, saepe in fascias conjuncta. 
Phaeophora granuliformia, sparsa.' 
Conspectus generum 
Dimeregramma Ralfs. — Valvae nodulo centrali carentes, intlnlae 
contractaeve ; frustula cobaerentia, e zona connectivali visa qua- 
drangula. 
Glyphodesmis Grev. — Valvae pseudorbaphe instructae, séries tran- 
sversales granulorum in areolis clalhratis praebentes, pseudono- 
duH et medianus et terminales distincli. 
Omphalopsis Grev. — Valvae cruciformes, striis transversis inter- 
ruptis (non clathratis) ornatae; pseudonodulus medianus distin- 
ctissimus. 
Plogiogramma Grev. — (ffeteromphala Ebr. 1858?) Valvae spa- 
tio centrali byalino (plerumque transversali) et pseudocello cen- 
trali saepius minutissimo donatae, costis paucis validis trans- 
