NAIADES OF MISSOURI 25 
of Amblema (Raf.) because of Simpson’s and Ortmann’s treatment, 
(preceded by that’of Morch in 1853) Schiilter’s name cannot be 
used. Thus it may be seen why an original name, ‘‘ Megalonazas,”’ 
(etymologically embodying a chief character) is herein submitted. 
\ 
Megalonaias heros (Say) 
(‘‘Giant Heros,” ‘‘ Washboard.’’) 
PEW We sets oO) abe VEX DL aes. as AF 
1829— Unio heros Say, New Harm. Diss., II, No. 19, p. 291. 
1831— Unio multiplicatus Lea, Tr. Am. Phil. Soc., IV, p. 70, Pl. 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. 
Fic. 2. Megalonaias heros (Say). Q Diagram of a gravid individual 
from Platte River, Garretsburg, showing animal characters 
in left valve. Coll. Jan. 25, 1913. (34 nat. 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 
