NAIADES OF MISSOURI 



43 



o( Amblema (Raf.) because of Simpson's and Ortmann's treatment, 

 (preceded by that of Mnrch in 1853) Schiilter's name cannot be 

 used. Thus it may be seen why an original name, " Megalonaias," 

 (etymologically embodying a chief character) is herein submitted. 



Megalonaias heros (Say) 

 ("Giant Heros," "Washboard.") 

 PL VII, Fig. 16; PL VXII, Figs. 48 A~F. 



1829 — Unio heros Say, New Harm. Diss., II, No. 19, p. 291. 



1831 — Unio multiplicattis Lea, Tr. Am. Phil. Soc, IV, p. 70, PI. IV, 



fig. 2. 

 1900b — Quadrula heros Simpson, Proc. U. S. Nat. Mus., XXII, p. 770. 

 1912b — Crenodonta heros (Say) Ortmann, An. Car. Mus., VIII., p. 248. 



Fig. 2. Megalonaias heros (Say). 9 Diagram of a gravid individual 



from Platte River, Garretsburg, showing animal characters 



in left valve. Coll. Jan. 25, 1913. (K "at. size.) 



ANIMAL CHARACTERS. 



Nutritive Structures: — Branchial opening very large, 

 with comparatively few and small papillae branched at their 

 tips; anal large, very finely dentate on outer edge; supra-anal 

 immense, slightly but distinctly separated from anal by mantle 



