188 THE LAND AND FRESH-WATER MOLLUSCA. 
Fam. Sphaeriidae. 
Sphaerium corneum (Zin.).—Possil M.; Forth and Clyde Cnl. (D.); Paisley 
Cnl. (C.). Locally though not gen. c. 
S. lacustre (J/ill.).—Possil M.; Forth and Clyde Cnl. at Firhill, possibly 
introduced (B. D.). 
Pisidium amnicum (J/ill.).—Glasgow and Paisley Cnl. (C.); R. Clyde above 
Rutherglen Bridge (B.). 
P. fontinale (Drap.).—Possil M.; ditch between Frankfield and Hogganfield 
(B.); E. Tarbert (T.). 
var. henslowana (Shepp.).—Glasgow and Paisley Cnl. (Mihi.). 
P. pusillum (Gmelin).—Possil M. ; nr. Cloch L. H. (B.) ; Tarbert (C.); L. Fad 
and L. Ascog (R.). 
P, nitidum, Jenyns.—Frankfield L. (B.); pools by side of road bet. Port- 
Glasgow and Kilmalcolm (fide J. G. Jeffreys) (G.); L. Fad (R.). 
Sub-Order Heteromya. 
Fam. Mytilidae. 
Dreissena polymorpha (Pailas).—Forth and Clyde Cul. ; ¢., not native (B.) ; 
Paisley Cnl. (C.). . 
