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 
Stype-- 
DysNomiIA (TRUNCILLOPSIS) BREVIDENS (Lea), 1831 
Type locality: (Incorrectly given as Ohio) corrected by 
Lea, 34, p. 85, to Cumberland River. 
Obliquaria interrupta Rafinesque, ’20, p. 302. 
Unio brevidens Lea, ’31 (not ’34, as given by Simpson), p. 75, pl. 6, 
tO: 
U. interruptus Raf. = U. brevidens Lea, Conrad, ’34, p. 69; Ferussac, 
35, p. 28; Conrad, ’38, p. 88, pl. 48. 
_ Truncilla brevidens (1.ea), Simpson, ’14, p. 7. 
Truncilla brevidens (Lea) = Obl. interrupta Raf., Vanatta, ’I5, p. 
550 (“type”’ examined). 
Tr. brevidens (lea) = Obl. interrupta Raf., Walker, ’16¢, p. 45; ’18¢, 
p. 186 (“if identifiable”). 
Tr. interrupta (Raf.), Ortmann, ’18, p. 586. 
Vanatta’s view. that Obliquaria interrupta Raf. is preoccu- 
pied by Unio solenoides interrupta 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 imterrupta 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 considered. Rafin- 
esque says, “Found in the Kentucky and Ohio rivers.” Sa 
far as we have been able to ascertain, there is no record of the 
