Occasional Papers of the Museum of Zoology 53 



Syviph. leptodon Raf. ^6'. tenuissima l^ta.^= An. pnrpurascciis S\v. 

 =1 U. planus Bar., '23, Ferussac, '35, p. 25; Conrad, '36, p. 58, pi. 33. 

 Lampsilis leptodon (Raf.), Simpson, '14, p. 188. 

 Leptodca leptodon Raf., Frierson, '14*, p. 6. 

 Lasmonos leptodon (Raf.), Utterback, '16, p. 156. 

 Paraptara leptodon (Raf.), Ortmann, '18, p. 571. 



There is no doubt about the specific name leptodon Raf. and 

 all authors have accepted it. Description and figures are 

 entirely satisfactory. 



However, with regard to the validity of the generic name 

 Lasmonos Raf., it is important to know what Lasmonos fra- 

 gilis Raf., '31, is. Rafinesque does not quote his Unio {Lep- 

 todea) fragilis of '21 under it, and thus we are to assume that 

 it is different. The chief character of this shell is the rudi- 

 mentary condition of the cardinal teeth, and this suggests that 

 it might be leptodon. However, it fits also certain phases of 

 L. fragilis (Raf.), '20. The rest of the description does not 

 clear up matters, since a sub-oval, thin shell, olivaceous out- 

 side and purplish inside, fits both species, and the posteriorly 

 broader shell with a small wing rather points to fragilis '20. 

 The words "some nodulities behind" fit neither. Thus Las- 

 monos fragilis is not identifiable and Lasmonos cannot be used 

 under any conditions. 



Leptodea Eragius (Rafinesque), 1820 

 Type locality: Ohio River. 



Unio (Leptodea) fragilis Rafinesque, '20, p. 295. 



Unio gracilis Barnes, '23, p. 174. 



Lasmonos fragilis Rafinesque, '31, p. 5. 



Unio fragilis Raf. = t/. gracilis Bar., Conrad, '34, p. 69; Ferussac, 

 '35. p. 25; Conrad, '36, p. 55, pi. 30; Frierson. 'I4^ p. 7. 



Lampsilis gracilis (Bar.), Simpson, '14, p. 181. 



Lampsilis fragilis (Raf.)=Z,. gracilis (Bar.), Vanatta, '15, p. 552 

 ("type" examined). 



Lasmonos fragilis Raf., Utterback, '16, p. 152 (quotations in part 

 incorrect). 



