240 BRITISH MOLLUSKS. 



4. Cyclas ovalis. Oval Cyclas. 



Shell ; oblong-oval, thin, rather compressed, smooth, marked con- 

 centrically at intervals with striae of growth, 

 bluish white, covered with a pale yellowish- 

 ash epidermis, nearly equilateral, sides ex- 

 pandedly rounded, the posterior being the 

 larger, umboes rather swollen, nearly central, 

 ligament slightly apparent. 



Cyclas lacustris, Draparnaud (1805), Hist. Moll-ip. 130, 



pi. x. f. 6, 7 (not Tellina lacustris of Muller). 

 Cyclas ovalis, Ferussac (1807), Ess. Metli. Conch. 2nd ed. 



p. 128 and 136. 

 Cyclas consobrina, Ferussac (1818), Blainv. Diet. Sci. 



Nat. vol. xii. p. 279. 

 Spharium Deshayesianum, Bourguignat (1853), Rev. Soc. 



Cuv. p. 345. 

 SpTicerium ovale, Bourguignat (1854), Mem. Soc. Phys. Bord. vol. i. 

 Sphcerium pallidum, Gray (1856), Ann. Nat. Hist. 2nd ser. vol. xvii. p. 465. 

 Cyclas pallida, Gray (1857), Turt. Man. p. 254. f. 61. 

 Sab. Central Europe. England. (In canals and ponds.) 



We are indebted to M. Bourguignat for having pointed out that 

 this species is the Cyclas lacustris of Draparnaud, which is not 

 the Tellina lacustris of Muller, a species more generally known as 

 C calyculata, Draparnaud. Ferussac made this observation within 

 two years of the publication of Draparnaud's mistake, and gave 

 the species the name, soon after abandoned, which is now restored 

 to it. The shell is of a rather compressed oval-oblong form, nearly 

 equilateral, and almost smooth, the surface being marked at dis- 

 tant intervals with rather prominent lines of growth. 



Among the chief characters of the species is its pale drab colour. 

 Six years since, some specimens of C. ovalis brought to Dr. Gray 

 from the Grand Junction Canal, near Kensal Green, were observed 

 to be distinct from any other species described in his 'Manual,' 

 and were named by him C. pallida. The animal he described as 

 having the foot large, and the siphons united nearly to the tip with 

 the apices conical. Mr. Daniel also collected specimens in the 

 Surrey Canal. "A living specimen," says Mr. Jeffreys, "taken 

 early in February, and kept in a vessel by itself, gave birth about 

 three weeks afterwards to some young ones at intervals of two or 

 three days. Immediately on being excluded they were very active, 



