Algee, Bacillai-ie?e, Rhaphidefe, Cymbellacese, Cymbella, 11 



1. Pleurosigma formosum W. Sm., iu .\nu. Nat. Hist., 1852, pag. 5, 35 

 I.. I, f. 1. Castrac, Atti Acc. Pont. N. Lincei, 18 Marzo 1877. — 

 Valvis anguste lanceolatis, longitudine variis, pleruuiqne 350-450 o., 

 longis, valde sygmoideis, apicibus subobtusis ,^vel passim acuiuinatis), 

 rliaphe valde excentrica, eximie sygmoidea; striis transversis deli- 

 catissimis, 1-1-17 in 10 [j.., striis obliquis conspicuis, sub angulo recto 

 invicem intersectis, 10-12 in 10 u.. 



In tripoli ad montes Labronicos Tuscice (Castrac). 



Gen. Mastog^loia Thwait., in W. Sm,, l^r. Diat., II, p. 65, t. 54, 

 f. 341. 



Frustuia navicuhieformia, rectangulari-oblonga, Scepius in pseudo- 

 thallo gelatinoso plus minus mamillcso nidulantia; valvaj loculis mar- 

 ginalibus e laminis siliceis inter membranam connectivalem et valvam 

 positis efformatis preditee. 



1. Mastogloia apiculata W. Sm., Br. diat., II, pag. 65, t, LXII, f. 387. 37 

 Castrac, Atti Acc. pont. N. Lincei, IV, 18 Marzo 1877, p. 245, — 

 Valvis ovato- vel elliptico-lanceolatis, 40-75 ^ 16-20, apicibus pro- 

 ductis obtusis, loculis abbreviatis, 30-50, irregularibus, area elli- 

 ptico-lanceolata; striis transversis parallelis, subrectis, teste W. Sm. 

 15 in 10 V.,, lineam mediara triplicem attingentibus, nodulo centrali 

 orbiculari vel oblongo. 



In tripoli messiniano ad Montes Labronicos Tuscicu (Castr,). 



Fam. CYMBELLACE^ 



Gen. Cymbella Ag., Consp., p. 1. 



Frustula libera vel stipitata; valvse plus minus cymbiformes, ar- 

 cuata?, a rhaphe noduloque centrali excentrico (margini approximato) 

 in partes duas inapquales divisa^. Rhaphe plus minus arcuata. 



1. Cymbella gastroides Kuetz., BacilL, pag. 73, t. 6, f. Ab. Castrac, 

 1 c, p. 6. Pant., 1. c, p. 7. De Toni, Syll. Algar., II, p. 361. — 

 Valvis late cymbiformibus ad 180 y.. longis, apicibus obtusis, ro- 

 tundatis, margine dorsuali arcuato, medio vix magis inflato, ventrali 

 lenissime concavo medioque subprominente; rhaphe leniter arcuata, 

 zona hyalina ampla, circa nodulum centralem elongatum paullo di- 

 lata*a cincta, nodulis terminalibus validissirais, striis transversis 

 robustis, 8 in 10 y... grosse raargaritatis. 



38 



