lo SPH^RIID^. 



thin, very glossy, with fine, regular, concentric striae, and 3-5 

 broadish ribs near the beaks, yellowish white or pale horn- 

 colour ; epidermis extremely thin ; anterior side rounded, 

 slightly truncate ; posterior side somewhat produced, sloping 

 abruptly downwards ; lower margiti rounded ; beaks prominent, 

 almost central, blunt ; ligament short, almost invisible ; insid& 

 whitish ; hinge and teeth as in P.fontinale; scars distinct. 



Inhabits lakes, and ponds throughout Great Britain. 

 This species differs from the rest of the Pisidia in its 

 more glossy and iridescent appearance, and stronger 

 striae, as well as in its siphon being ftmnel-shaped and 

 having the margin notched or puckered. 



Van splendens. — Shell lemon-coloured, much larger, not so 

 glossy ; stricE fainter ; beaks more swollen ; ligament stronger, 

 more apparent. Lakes near Lerwick, and at Balmacarra in 

 West Ross, B.C, 



D. Oblong, 



5. P. RO'SEUM,* SCHOLTZ. Pl. I. 



Body " opaline- white, orange -yellow, red, or rose-colour in the 

 upper part ; tube long, slender, subconical, and truncate at its 

 orifice ; foot long, semitransparent." — B.C., vol. i. p. 26. 



Shell somewhat oblong, swollen, thin, extremely glossy, with 

 strong, regular, concentric striae, yellowish- white or pale horn- 

 colour ; epidermis very thin ; anterior side truncate, sloping 

 downwards ; posterior side elongated and rounded ; lower 

 7nargin almost straight ; beaks prominent, blunt, placed away 

 from the centre ; liganient almost invisible ; inside whitish, 

 pearly ; cardinal teeth very small ; lateral teeth small, outer 

 edges strong, sharp ; scars very slight. 



Inhabits ponds, ditches, &c., throughout the British 

 Isles. This species bears some resemblance to P, 

 nitidum in its sculpture and glossy surface, but may 



Rose-coloured. 



