44 NAIADES OF MISSOURI 
Unionidae.’ For other personal help while attending the Uni- 
versity thankful acknowledgements are due to Dr. R. L. Moodie, 
Messers. G. T. Kline and F. A. Simpson. Under the illustra- 
tions of the new species (Plates v and vi) credit is given Mr. 
Kline, the University Artist-technician, for his excellent draw- 
ings. Through the kindness of Mr. Sampson, author of the 
‘Mollusca of Missouri’? (Exclusive of the Unionidae), permis- 
sion has been given to examine his, collections of mussel shells 
and make use of his list for same in determining geographic 
distribution and in confirming the reports of other Missouri 
collectors. Mr. B. F. Bush, a well-known scientist, and resident 
of Courtney, Mo., has rendered invaluable aid in sending for 
study immense collections taken mostly from the Ozark region 
where the author has not been permitted to carry on such exhaus- 
tive field studies as in the northern part of the State. Material 
from Missouri, contributed to the author’s collection by Messrs. 
C. C. Crouch of LaGrange, E. J. Palmer of Webb City and D. K. 
Gregor of Fulton, has been thankfully acknowledged. The writer 
is deeply indebted to old collectors and authors, who were former 
residents of this State, viz:— Messrs. C. T. Simpson, W. A. Marsh, 
Elwood Pleas and Dr. John H. Britts; also to those students of 
Navades for the nearest surrounding States viz:—Dr. F. C. Baker of 
Illinois, Rev. W. E. Wheeler of Arkansas, Dr. D. H. Wolcott of 
Nebraska, Dr. Junius Henderson of Colorado, Prof. F. B. Isely 
of Oklahoma and Drs. R. E. Coker, Thaddeus Surber, A. D. 
Howard, Prof. H. Walton Clark of Iowa. The last four named 
students are of the personel of the U. S. Fisheries Biological Labora- 
tory, located along the Mississippi at Fairport, Iowa, where the 
author has done some study and has had pleasant personal contact 
with these gentlemen who have contributed so much to the science 
of Fresh-water Mussels. Besides being under obligations to the 
above-named for their literary and conchological exchanges, as 
well as for their valued correspondence and actual personal assist- 
ance, special mention would also be made of Drs. A. E. Ortmann, 
V. Sterki, C. B. Wilson, W. H. Dall, Harold Hannibal and Messrs. 
B. H. Wright, Bryant Walker and L. S. Frierson. The author is 
most grateful to Dr. Ortmann as an authority concerning the soft 
parts, to Mr. Walker for his treatment of the shell parts and to 
Mr. Frierson for his general knowledge of Natades as well as for his 
special information concerning the Southwest forms. Through 
