THE NAIADES OF MISSOURI 447 
of beaks deep, of the shell moderately deep. Nacre white, decidedly 
irridescent posteriorly.” 
Dr. Scammon reports Powellii as a very rare shell for Kansas, 
being found in only one locality, Spring River, Baxter Springs, 
and further states that this species may be distinguished from 
L. luteola, its nearest ally in local waters, by the smaller and less 
pointed cardinals and the thinner, squarer and less inflated shell. 
_ Simpson states that Powellii is alsofound in Salina and Clinton, 
Arkansas, and in Guadaloupe River, Texas. The fact that Mr. 
Simpson found this rare shell in the Neosho basin of this State 
its range is more determined. 
Lampsilis luteola (Lamarck). 
(“Fat Mucket.’’) 
Pl. XXVIII, Figs. 103 A—F. 
1819— Unio luteola Lamarck, His. Sans. Vert., VI, p. 79. 
1898—Lampsilis luteola Baker, Mol. Chicago, Pt. I, p. 103, pl. XI, 
fier ne pla XEXOXOVAL,: fig: 12. 
ANIMAL CHARACTERS. 
NUTRITIVE STRUCTURES:—Branchial opening large with 
numerous papillae; anal slightly crenulated; supra-anal well 
separated by thick mantle connection; inner laminae of inner 
gills connected to visceral mass; palpi short, wide; color of soft 
parts dingy white, mantle border blackened posteriorly. 
REPRODUCTIVE STRUCTURES:—Mantle edge antero-ventrad to 
branchial opening with long spotted flap at the end of which are 
two or three finger like tentacles and about midway an eye spot 
appears; marsupium large, kidney-shape, consisting of numerous 
distinct ovisacs that hang down toward the mantle flap in beaded 
rows; conglutinates white, large, subsolid; glochidium rather 
large (uniformly smaller for lacustrine /uteola), subelliptic, spineless, 
measuring 0.250 x 0.290mm. 
SHELL CHARACTERS. 
EXTERNAL STRUCTURES:—Shell broadly elliptic, narrowly 
rounded before, broadly rounded behind; female shell greatly 
inflated, rather truncated posteriorly expanded post-ventrad, male 
shell pointed posteriorly; disk smooth; umbones large but low, 
