CYM BELLA. 



M5 



Considerably longer than the preceding, with apices much more 

 rostrate, ventral margin almost straight and strongly gibbous. Length 

 3.5 to 4 c.d.m. 



Freshwater. Louvain, Brussels, Antwerp, etc. 



C. microcephala Grun. (h.v.h. Atl. pi. 8, f. 3639*- in Type 

 No. 211), plate 1, fig. 34, 34. 



Valves rather narrowly lanceolate, scarcely cymbiform, with apices 

 strongly rostrate-capitate; raphe sub-arcuate; stria? delicate, 24 in large 

 forms, 28 to 30 in small forms. Length 1.5 to 2.3 c.d.m. 



Fresh water. Brussels (Delogne). 



C. tumidula Grun. (in Ad. Schm. Atl., pi. 9, f. 33 * ; h.v.h. 



Type No. 27 sub 110m. C. affinis var. tumidula); plate 25, fig. 697. 



Valve linear-lanceolate, with rostrate apices. Dorsal margin very arcuate ; 

 ventral margin straight or slightly gibbous at the median portion. Raphe 

 somewhat eccentric; surrounded by a narrow hyaline area. Striae about 14 

 in 1 c.d.m., somewhat radiant, punctate, shortened on the dorsal side round 

 the central nodule, where they leave a small rounded hyaline area, while on 

 the ventral side each of the two median striae are terminated by a distant 

 isolated dot. Length y$ to 3*5 c.d.m. Breadth 0*75 to 10 c.d.m. 



Fresh water. England (Thames, Oxford (F. Okeden) ). 



This form is very closely allied to C. affinis, and it has been recorded 

 with it by \V. Arnott and Grunow. The dorsal, median, hyaline area 

 does not exist in C. affinis ; in that form there is seen on the ventral side 

 one coarse isolated dot, but never two, the striae also are in an equal 

 manner more robust and more distant. 



Naviculoid, sub-lanceolate-linear valve, both margins scarcely bent, 



almost straight, striae delicate. 



C. aequalis W. Sm. (S.B.D. ii., p. 84; Ad. Schm. Atl, pi. 9, f. 

 69*) plate 25, fig. 698. 



Valve lanceolate almost naviculoid, with dorsal margin regularly arcuate, 

 slightly produced at apex. Ventral margin rather more strongly arcuate, 

 with apices rostrate-capitate. Raphe and central nodule surrounded by a 

 well marked hyaline space. Striae delicate, about 12-13 in 1 c.d.m. Length, 

 3"5 to 6 cd.m. 



Fresh water. England, various localities ; Germany, etc. ? According to Prof. Cleve, this 

 form should be the C. angustata of W. Sm. 



L 



