146 CYM BELLA. 



C. abnormis Grun. (in H.V.H. Syn., pi. 3, f. 8*; Bot. Centbl, 

 1880, p. 249), plate 25, fig. 699- 



Valve sub symmetrical with apices slightly produced, dorsal margin arcuate, 

 ventral margin almost straight, slightly inflated at the median portion. Raphe 

 straight, surrounded by a rather broad hyaline space. Striae rather strong, not 

 moniliform, very distant, about 10 in i c.d.m. : absent in median portion 

 where they leave a broad stauroform blank space. Length, about 2-5 c.d.m. 

 Breadth, o - 5 c.d.m. 



Fresh water France (Normandy), Sweden, Norway (Grunow) 



Sec. II. Ventral and dorsal margins bent in the same direction ; 

 raphe with concavity turned towards the ventral margin. 



% Terminal nodules not very elongate. 



[a.) STRIATION NOT INTERRUPTED BY A BROAD HYALINE SPACE ON 

 THE VENTRAL SIDE OF THE VALVE. 



C. gastroides KutZ. (Baa, p. 79, pi. 6, f. 4 b ; H.V.H. Atl., pi. 2, 

 f. 8* ; Type 20) plate 1, fig. 35. 



Valve broadly cymbiform with apices obtuse, rounded ; dorsal margin 

 arcuate, with median portion scarcely more inflated ; ventral margin very 

 slightly concave, with median portion somewhat prominent ; raphe slightly 

 arcuate, surrounded by a very broad hyaline zone, very slightly dilated round 

 the central nodule ; central nodule elongate ; terminal nodules very robust ; 

 striae very robust, 8 in 1 c.d.m., consisting of coarse distant beads. Length, 

 about 15 c.d.m. 



Fresh water. Rather common. 



/3. minor. (H.V.H. Atl., pi. 2, f. 9*) plate 1, fig. 36. 



Short, very broad, with raphe strongly arcuate. Length, 7 to 8 c.d.m. 



Fresh water. Not so common as the type form. 



C. lanceolata Ehr. (Coxonewa lanceolatum Ehr. Inf. p. 224, 

 pi. 19, f. 6; H.V.H. Atl., pi. 2, f. 7*; Type No. 18), plate 1, fig. 37. 



Valve cymbiform with dorsal margin strongly convex, ventral margin 

 concave, inflated at the median portion ; apices obtuse, raphe very arcuate, 

 surrounded by a very narrow hyaline zone, scarcely dilated near the central 

 nodule ; central nodule rather large, elongate ; terminal nodules of medium 



