I am grateful to L. C. Stuart of the University of Michigan, who made
the initial arrangements for our work in El Peten, aided me in the
identification of certain specimens, and helped in the preparation of
this report. J. Knox Jones, Jr. and John Wellman were able field
companions, who added greatly to the number of specimens in the
collection. In Guatemala, Clark M. Shimeall and Harold Hoopman of the
Ohio Oil Company of Guatemala made available to us the facilities of the
company's camps at Chinaja and Toocog. Alberto Alcain and Luis Escaler
welcomed us at Chinaja and gave us every possible assistance. Juan
Monteras and Antonio Aldana made our stay at Toocog enjoyable and
profitable. During our visits to southern El Peten, Julio Bolon C.
worked for us as a collector, and between March and June he collected
and saved many valuable specimens; his knowledge of the forest and its
inhabitants was a great asset to our work. Jorge A. Ibarra, Director of
the Museo Nacional de Historia Natural in Guatemala assisted us in
obtaining necessary permits and extended other kindnesses. To all of
these people I am indebted for the essential parts that they played in
the completion of this study.
Field work in the winter of 1960 was made possible by funds from the
American Heart Association for the purposes of collecting mammalian
hearts. My field work in the summer of 1960 was supported by a grant
from the Graduate Research Fund of the University of Kansas.