I am grateful to Professor Frank B. Cross for his interest in my
investigation, for his counsel, and for his penetrating criticism of
this paper. This study would have been impossible without the assistance
of several persons who helped in the field. Mr. Artie C. Metcalf and Mr.
Delbert Metcalf deserve special thanks for their enthusiastic and
untiring co-operation in collecting and preserving of specimens. Mrs.
Artie C. Metcalf, Miss Patricia Metcalf, Mr. Chester Metcalf, and Mr.
Forrest W. Metcalf gave help which is much appreciated. I am indebted to
the following persons for numerous valuable suggestions: Dr. John
Breukelman, Kansas State Teachers College, Emporia, Kansas; Dr. George
Moore, Oklahoma A&M College, and Mr. W. L. Minckley, Lawrence, Kansas.