144 CYMBELLA. 



straight, slightly arcuate, not gibbous ; raphe almost straight, slightly flexuous, 

 surrounded by a very narrow hyaline zone, in no parts inflated ; stria? 

 delicate, slightly radiant, visible with difficulty; dorsal 18, ventral 22 in 1 c.d.m. 

 Length about 3 to 4 c.d.m. 



Freshwater. Frahan, Belgium (Delogne); Aid. Lidge. (DeWild. ) 



C. laevis Naegeli ! (h.v.h. Atl., pi. 3, f. 7*; in Type No. 257); 

 plate 1, fig. 30. 



Valves lanceolate, with dorsal margin very arcuate, ventral margin very 

 slightly convex. Apices very shortly rostrate, rostrum narrow. Raphe very 

 slightly arcuate, surrounded by a narrow hyaline zone ; striae faintly marked, 

 14 in 1 c.d.m. Length about 3 c.d.m. 



Fresh water. Ard. Lige. (De Wild.) ; S. Abbe Head, England. 



Var. rupicola Grun. (C. ruphola Gr. in A. Schm. Atl., pi. 71, 

 f. 70-71*; in H.V.H. Type No. 28) ; plate 25, fig. 696. 



Differs only from the type form by its valves being somewhat more 

 symmetrical. 



Fresh water. Scotland. 



C. affinis Kiitz. (Bac, p. 80, pi. 6, f. 14 ; H.V.H. Atl., pi. 2, f. 19* ; 

 Type No. 26); plate 1, fig 31. 



Short, ventricose ; valves broadly lanceolate, with dorsal margin very 

 convex, ventral margin very slightly convex, not gibbous ; apices produced 

 rostrate ; raphe very arcuate, parallel to dorsal side, surrounded by a narrow 

 hyaline zone; stride median, dorsal 9, ventral n in 1 c.d.m. Length 2*5 

 c.d.m. 



Fresh water. Antwerp, Brussels, Louvain (H.V.H.) ; England (W. Sm., Norman); Scotland 

 (Greg.) ; Ireland (W. Sm., O'Me.) 



C. leptoceras Kiitz. (Bac, p. 79, pi. 6, f. 14; h.v.h. Atl., pi. 3, 



f. 24* ; in Type No. 211) plate 1, fig. 32. 



Valves rather broadly lanceolate, short, with apices attenuate, sub-obtuse ; 

 dorsum very arcuate, ventral margin extremely gibbous ; raphe almost 

 straight, slightly flexuous, surrounded throughout its length by a rather broad 

 hyaline zone; striae well marked, about 8 in 1 c.d.m. Mean length, 2 to 

 3 c.d.m. 



Fresh water. Brussels, Antwerp, &c. 



Var (3 elongata (C. leptoceras H.V.H. Atl., pi. 3, f. 18 ; suppl., 

 f. 2* ; in Type No. 211) plate 1, fig. 33. 



