CYMATOPLEURA. 367 



ANALYSIS OF SPECIES. 



Valves broadly elliptic or elliptic lanceolate . C. elliptica. 



Valves linear, with apices generally rostrate rj Solea 



C. elliptica (Breb.) W. Sm. (S.B.D., i., pi. 10, f. 80 ab; 

 H.V.H. Atl., pi. 55, f. 1*), plate 12, fig. 480 b. 



Valve broadly elliptic or elliptic lanceolate, with margins furnished with 

 short costse simulating coarse beads ; striae delicate, 18 in 1 c.d.m. Girdle 

 face showing a small number of undulations. Length, 8 to 14 c.d.m. 



Fresh water. Rather common throughout Europe. 



var. constricta Grun. (H.V.H. Atl-, pi. 55, f. 2*), plate 12, fig. 

 481 b. 



Valves longly elliptic, slightly constricted at the median portion. 



var. Hibernica. (C. Hibernica IV. Sm. ; H.V.H. Atl., pi. 55, f. 3-4*), 

 plate 31, fig. 863. 



Valve broadly oval, with apices somewhat acuminate-rostrate. 



Fresh water. Not yet found in Belgium. Ireland (W. Sm.), Scotland (Dickie), France 

 (De Bntoison). 



C. Solea Breb.) W. Sm. (S.B.D., i., pi. 10, f. 78; H.V.H. 



Atl., pi. 55, f. 5-7*), plate 12, fig. 482 . 



Valves more or less longly linear, with apices generally rostrate, median 

 portion constricted, margins furnished with somewhat longer costte than in 

 the preceding species, and showing coarse moniliform striae, about 6 in r 

 c.d.m. 



In very oblique illumination the striation shown in fig. 482 (left-hand 

 figure) may be seen. Girdle face very narrow, and showing a large number of 

 undulations, sometimes opposite, sometimes alternate. Length, 5 to 13 

 c.d.m. 



Fresh water. Rather common throughout Europe. 



var. regula (Ehr.) Ralfs. 



Valve with parallel margins, not constricted in the median portion. 



