EUNOTIA. 301 



forma curta. (H.V.H. Atl., pi. 33, f. 15*), plate 9, fig. 370. 



Small, almost straight. 



forma elongata. (H.V.H. Atl., pi. 33, f. 16*), plate 9, fig. 371. 



Long, feebly arcuate. 



var. ventricosa Grun. (H.V.H. Atl, pi. 33, f. 19^*), plate 9, fig. 

 372. 



Ventral margin showing an embossment in the median portion. 



var. undulata Ralfs. (H.V.H. Atl., pi. 33, f. 17*; Type No. 265), 

 plate 9, fig. 373. 



Ventral margin showing a median embossment, dorsal margin with 

 three to five embossments. 



var Soleirolii Kiitz. (H.V.H. Type, No. 266). 



Form with septate frustules (double internal valves) in consequence of 

 an imperfect division. 



E. Faba. (Ehr.) Grun. (Himantidium Soleirolii IV. Sm, part ; 

 H.V.H. Atl., pi. 34, f. 34*; in Type No. 274), plate 9, fig. 374. 



Valve reniform, elongated, with somewhat visible striae, 10 to 12 in 1 c.d.m., 

 finely divided transversely ; girdle face almost always showing septa arising 

 from an imperfect division {var. Soleirolii W. Sm.). Length, 3 to 5 c.d.m. 



Fresh water. Not yet found in Belgium, very doubtful if indigenous. France, England 

 (Comber), Scotland, Ireland (O'Meara). 



77. Frustules not united in filaments. 

 a. Frustules free, not parasitic on other plants. 



E. Veneris KlitZ. (Baa, p. 40, pi. 30, f. 7 ; E. incisa Greg. ; 

 H.V.H. Atl., pi. 34, f. 35 A*), plate 30, fig. 826. 



Valve of medium size, with ventral margin almost straight, dorsal margin 

 arcuate, apices subacute. Striae fine, 16 or 17 in 1 c.d.m. Length, about 

 4 c.d.m. 



Fossil. Mull deposit, Scotland (Gregory). 



var. obtusiuscula Grun. (H.V.H. Atl., pi. 34, f. 35B* ; in Type 

 No. 271). plate 30, fig. 827. 



Ventral margin somewhat concave, apices obtuse. 



Fossil. Sweden, England. 



E. tridentula Ehr. (Verb., p. 126, pi. II., i, f. 14; H.v.H. Atl, 



pi. 34, f. 31 var* ; in Types Nos. 309 and 347), plate 9, fig. 375. 



