THE NAIADES OF MISSOURI 245 
1912b— Uniomerus tetralasmus (Say) Ortmann, An. Car. Mus., VIII, 
pp. 272 and 273. 
Fic. 4. Uniomerus tetralasma (Say) 9. Diagram of a gravid individual 
from Lost Cr., Amity, showing animal characters in left valve. 
Coll. May 3, r913. (34 nat. size.) 
ANIMAL CHARACTERS. 
NUTRITIVE STRUCTURES:—Branchial opening large, set with 
numerous papillae; anal finely crenulate on inner edge; 
supra-anal large extending to dorsal line, closed from anal by a 
moderate mantle connection; gills about the same width, inner 
‘onger, inner laminae free from visceral mass for whole length 
except for a short distance anteriorly; palpi short and broad, 
connected only for one-fourth of their length antero-dorsad; 
color of soft parts, for most parts, a dingy white with mantle edge 
at siphonal openings blackish, gills brown. 
REPRODUCTIVE STRUCTURES:—Marsupia only occupying 
outer gills, when charged rather padiform, distended at center, 
but not near the ventral edges, ovisacs simple, undivided; con- 
glutinates also undivided, white, sole-shaped, with regular thin 
transparent areas arranged cross-wise made by the thickening 
of the septa at regular intervals; glochidia spatulate, very regular 
in outline, hinge line short and straight, medium in size measuring 
0.160 x 0.210 mm. 
