14 Algso, Bacillarieae, llliaphidese, Achnautliacere, Achnanthes. 



Fam. GOMPHONEMACEiE 



Gen. Gomphonema Ag., (182-1) Syst. Alg., pag. 15. 



Valvae naviculacei\ asymmetrica?, uno apice altero angu.stiori et 

 cuneiformi; facies frustulorum connectivalis, cuneiformis. Frustula 

 plerumque .sessilia v. stipitata. 



1. Gomphonema Vibrio Ehr., Verbr., pag. 128, t. 2, I, f. 40. Castrac, ^- 

 1 c, p. 7. Pant., 1. c, p. 7. De Toni, Syll. Algar., II, p. 427. — Valvis 

 lineari-lanceolatis, 60-85, a. longis, apicibus latis rotundatis, inter 

 se ina'qualibus, deorsum magis quam sursum attenuatis, nodulo cen- 

 trali distincto, oblongo-rotundato; striis transversis subradiantibus 

 9-12 in 10 7.. rhaphem non attingentibus; stipitibus elongatis. 

 In marga pliocenica inferiore agri Spoletini Umbriae (Castrac). 



Gcn. Rhoicosphenia Grun., 1860, in Wien Verhandl., X, 

 pag. 51 1. 



Valv;e cuneiformes dissimiles, superior tantum pseudorhaphen prse- 

 bens, nodulis carens, inferior rhaphem genuinam et nodulos osten- 

 dens. Frustula e facie connectivali visa arcuata. 



1. Rhoicosphenia curvata (Kuetz.) Grun , Alg. Novara, pag. 8. Gom- 40 

 phonema? cunmtum Kuetz., Hacill., p. 85, t. VIII, f. 1; Castrac, 

 1. c, p. 7; Pantan., 1. c, p. 7. — Valvis e basi cuneata obovato- 

 lanceolatis 15-65 y.. longis, apice super-obtu.so-rotundatis, valva su- 

 periori .'^triis parallelis robustis omnibus pseudorhaphen attingenti- 

 l)us, circiter 10 in 10 y..; valva inferiori striis radiantibus, circiter 

 12 in 10 -j-. rhaphe zona hyalina parva circa nodulum centralera di- 

 latata cincta, stipite frustula gerente plus minusve elongato simplici 

 vel diviso. 



In marga pliocenica inferiore agri Spoletini, Umbrias (Castrac). 



Fam. ACHNANTHACEiB 



Gen. Achnanthes Bory, Dict. class., I, p. 79. 

 Valviij liueares vel ellipticaa pleruraque stipitatfc costis transversis 

 vel striis transversis punctatis donatffi, rhaphe recta. 



1. Achnanthes longipes Ag., Syst., pag. 1 Castrac , Atti Acc. Pont. 47 

 N. Lincei, 18 Marzo 1877, pag. 245. — Valvis lineari-ellipti- 



