Lampsihs carinata (Barnes) Mucket 

 Actinonaias carinata (Barnes) 



98. Epidermis with a dull, mat or satiny finish and with obscure or no rays 



(color markings), except in some young shells; epidermis usually dark 



colored in adult specimens 99. 



Epidermis polished or rayed; epidermis usually, but not always, yellowish 



107. 



99. Cardinal teeth split up; practically no interdentum; Gulf States 



Glehida suhorbiculata (Lamarck) 

 Glehula rotundata (Lamarck) 

 Hinge not so 100. 



100. With practically no beak cavity; nacre usually purple; Mississippi 



drainage 



Elliptio niger (Raf.) Elephant's Ear 

 Elhptio crassidens (Lamarck) 

 Beak cavity impressed; nacre white or pink lOL 



101. Shell almost circular; Vv'ithout a posterior ridge; east-central states 



Ohovaria suhrotunda. (Raf.) Round Nigger-head 

 (Ohovana circulus (Lea)) 

 Shell oval or triangular; with or without a posterior ridge 102. 



102. Shell irregularly triangular or arcuate in outline; posterior ridge moder' 



ate to strong; anterior cardinal of left valve directed to anterior half 



of or before the anterior muscle scar 103. 



Shell ovoid; posterior ridge rounded or low; anterior cardinal of left 



valve directed to middle or posterior part of the anterior muscle scar 



105. 



103. Shell triangular, with swollen umbones; anterior cardinal of left valve 



directed before the anterior muscle scar; east-central and central states 



^uadrula undata (Barnes) Pig-toe 



Fusconaia undata (Barnes) 

 Shell more arcuate, with lower beaks; anterior cardinal of left valve 

 directed to the anterior half of the anterior muscle scar 104. 



104. Hinge with a wide, heavy interdentum; shell becoming large and heavy; 



Ohio, Cumberland and Tennessee drainages 



§^uadrida suhrotunda (Lea) Heavy Pig-toe 

 Fusconaia suhrotunda (Lea) 

 Hinge line thinner; shell more moderate; east-central and central states 

 ^uadrula fiava (Raf.) Wabash Pig-toe 

 Fusconaia flava (Raf.) 



105. With a low, rounded posterior ridge; nacre white or pink; anterior 



muscle scars seldom iridescent; east-central and central states 

 ^uadrula coccinea (Conrad) Pink Nigger-head 

 Pleurohema cordatum coccineum (Conrad) 

 With a low, faintly double posterior ridge; nacre usually white 106, 



106. Base line almost straight; Virginia to North Carolina 



Pleurohema suhplanum (Conrad) 

 Lexingtonia suhplanum (Conrad) 

 Base line curved; Tennessee drainage 



161 



