1 8 UN1ONW&. 



line rather curved, and raised on the posterior side, which is 

 produced to a long wedge-like point ; lower margin rounded. 

 West of Ireland, B.C. Near Birmingham (G. SherrifT Tye), J.C. 

 Var. 5. ro strata. Shell oblong-oval ; upper margin forming 

 a dorsal crest, which is slightly raised and curved ; anterior side 

 rounded ; posterior side attenuated, and ending in a long, curved, 

 wedge-like point ; lower margin nearly straight. River Corfe, 

 Dorset, ponds at Wistow, Leicestershire, Wynyard Park, Co. 

 Durham, and Oxford, B.C. 



2. A. ANATI'NA,* LINN. PL. II. 



Body nearly oval, somewhat compressed, grey of various 

 depths of colour ; foot yellowish or reddish-grey ; mantle brown 

 at its edges ; gills dirty grey. 



Shell oval, somewhat compressed, rather thicker than the last 

 species, olive-green or brown, banded in the line of growth with a 

 darker colour, usually rayed with green and irregularly wrinkled ; 

 epidermis thin but slightly stronger than in A. cygnea; beaks 

 straight, not central ; umbonal region compressed, plaited ; 

 ligament short, prominent ; hinge line curved, and considerably 

 raised ; anterior side rounded, sloping obliquely below, gaping ; 

 posterior side curved, sloping obliquely downwards to a wedge- 

 shaped point ; lower margin slightly curved ; inside white, 

 pearly, iridescent ; hinge as in last species ; scars deeper than 

 in A. cygnea. 



Inhabits situations similar to those where A. cygnea 

 occurs. Considerable difference of opinion exists 

 among conchologists as to whether A. anatina should 

 be regarded as a distinct species, or merely a variety 

 of A. cygnea. In the 'Annals and Magazine of Nat 

 Hist/ 4th series, vol. v. p. 66, Mr. R. M. Lloyd makes 

 the following remarks : 



" It has been maintained that these animals are 

 varieties, because no difference is to be found in their 



Belonging to (i. e. food for) ducks. 



