1 8 UNIONID^. 



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

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

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

 Var. 5. rostrata. — Shell oblong-oval ; upper margin forming 

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

 rounded -, posterior j-/^*? 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,* LlNNfi. Pl. II. 



Body nearly oval, somewhat compressed, grey of various 

 depths of colour*; /<?<?/ 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. cygneaj beaks 

 straight, not central ; tiinbonal 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 ^. 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. 



