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.