66 University of Michigan 



The generally accepted identity of Tr. triquetra Raf., which 

 is evident from description and figure, has been confirmed by 

 Vanatta's examination of the so-called Rafinesque-Poulson 

 "type." 



Dysnomia (Truncillopsis) brevidens (Lea), 1831 



Type locality: (Incorrectly given as Ohio) corrected by 

 Lea. '34, p. 85, to Cumberland River. 



Obliquaria intcrrupta Rafinesque, '20, p. 302. 



Unio brevidens Lea, '31 (not '34. as given by Simpson), p. 75, pi. 6, 

 f. 6. 



U. interrnptxis Raf. ^ L'. brevidens Lea, Conrad, '34, p. 69; Ferussac, 

 '35, p. 28; Conrad, '38, p. 88, pi. 48. 



Truncilla brevidens (Lea), Simpson, '14, p. 7. 



Truncilta brevidens (Lea)^Ofc/. interrupta Raf., Vanatta, '15, p. 

 550 ("type" examined). 



Tr. brevidens (Lea) = Obi interrupta Raf., Walker. 'i6c, p. 45; '18^, 

 p. 186 ("if identifiable"). 



Tr. interrupta (Raf.), Ortmann, '18, p. 586. 



\'anatta's view that Obliquaria interrupta Raf. is preoccu- 

 pied by Unio solenoides intcrrupta Raf. does not hold good 

 (Walker). However, the original description of O. interrupta 

 is not sufficient to recognize the species. 



It is evident that Rafinesque's type of his interrupta, if a 

 specimen of brevidens, was a male shell, no mention being 

 made of the characteristic posterior inflation and truncation 

 of the female brevidens. A normal male brevidens of exactly 

 the same length as the type of interrupta is 10% higher and 

 25% more inflated. Many specimens could be selected that 

 are proportionately higher. The proportions given by Rafin- 

 esque for his shell do not, therefore, agree with those of 

 brevidens. 



The question of locality should also be considsred. Rafin- 

 esque says, "Found in the Kentucky and Ohio rivers." So 

 far as we have been able to ascertain, there is no record of the 



