Occasional Papers of tlie Museum of Zoology 21 



either ground in giving clara Lam. as the type of Pleurobema, 

 because mytiloides is a synonym of clava. 



The designation of U. scalenius Raf. as the type of Scale- 

 naria by Herrmannsen makes this name a synonym of Pleuro- 

 bema (we choosing to give preference to the latter according 

 to Art. 23 of the Code, concerning names of the same date), 

 and renders the subsequent designation of another species by 

 Agassiz as the type of Scalenaria wholly inoperative. 



Pleurobema cordatum (Rafinesque), 1820 

 Type locality: Ohio River. 



Unio obliqiia Lamarck, '19, p. 72. 



Obliquaria lateralis Rafinesque, '20, p. 310. 



Obovaria cordata Rafinesque, '20, p. 312, pi. 82, figs. 6-7. 



U. obliqua Lam. = L'". uitdatiis Bar. ('23), Lea, '34, p. 28 (tj-pe 

 examined). 



U. cordatns Raf. = 17. obovata Raf. (for obovalis ?), Conrad, '34, 

 p. 68. 



U . triangularis Raf. = lateralis Raf. =: sintoxia Raf. z=pachostea Raf. 

 = viytiloidcs Rut. = rubra Rai. = pyramidatus Lea. Conrad, '34, p. 72. 



U. obliqua Lam. = obovalis Rai.^ ebenus Lea, Ferussac, '35, p. 28. 



U. cordatus (Raf.) Conrad, '36, p. 48, pi. 25. 



U. obliqutis Lam. = imdatus Bar. = cordattis Con., Lea, '38, p. 125. 



U. obliqnus Lam. and U. solidus Lea, Call, '00, pp. 501, 504, pi. 57, 59. 



Quadrula obliqua (Lam.), Simpson, '14, p. 881. 



Quadrula obliqua Lam. = Obliq. lateralis Raf., Vanatta, '15, p. 557 

 ( "type" examined ) . 



Qiuidrula cordata Raf. = Q. plena (Lea), Vanatta, '15, p. 558 ("type" 

 examined). 



Quadrula obliqua Lam. = obliq. lateralis Raf., Walker, '18'', p. 167 

 (fide Vanatta). 



That the description of U. obliqua Lam. is imperfect and 



that the species cannot be identified from it has been stated 



by Lea ('29, p. 422). Later ('34) he identified obliqua from 



the type as undatus Bar., which, as we see from his Synopsis 



in 1838, is the same as cordatus Con. ('36), while the real 



undatus is a Fusconaia and the same as trigonus Lea. See 



Fusconaia undata. 



