Transcribers Notes: Italics words are denoted by _underscores_. Bold words are denoted by =equals=. Whole and fractional parts are displayed as 7-3/4. Greek text has been transliterated and are denoted by ~tildes~. Male and Female symbols are represented by [M] and [F] respectively. UNIVERSITY OF KANSAS PUBLICATIONS MUSEUM OF NATURAL HISTORY Vol. 4, pp. 1-466, plates 1-41, 31 figures in text December 27, 1951 AMERICAN WEASELS BY E. RAYMOND HALL UNIVERSITY OF KANSAS LAWRENCE 1951 UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY Editors: E. Raymond Hall, Chairman, A. Byron Leonard, Edward H. Taylor, Robert W. Wilson Vol. 4, pp. 1-466, plates 1-41, 31 figures in text December 27, 1951 UNIVERSITY OF KANSAS Lawrence, Kansas PRINTED BY FERD VOILAND, JR., STATE PRINTER TOPEKA, KANSAS 1951 23-3758 [Illustration: PLATE 1. Coloration of head and foreparts in ten subspecies of long-tailed weasel, _Mustela frenata_. All figures are of males, approximately × 1/2. In regions of heavy rainfall (see figs. 2 and 3) there is an increase in pigmentation and extent of blackish color backward over the neck and a decrease in extent of the white facial markings. In regions progressively more arid (see figs. 3 to 7) there is a decrease in pigmentation and extent of blackish color and an increase in extent of the white facial markings. As shown by rearing mammals from humid regions in arid regions, and _vice versa_, the color is not visibly altered in one or a few generations; the color is an hereditary character. Beginning with the southernmost subspecies (fig. 1) and continuing northward to the northern subspecies (fig. 10) there is a darkening, next a lightening, and finally a darkening closely conforming to amounts of precipitation in the geographic regions concerned. A fuller discussion of this correlation is given on page 51.] [Illustration: FIG. 1. Map showing localities of capture of specimens depicted in plate 1.] American Weasels BY E. RAYMOND HALL CONTENTS PAGE INTRODUCTION 7 PALEONTOLOGICAL HISTORY 10 SKELETON AND DENTITION 12 DISPARITY IN NUMBERS OF MALES AND FEMALES 19 MATERIALS, ACKNOWLEDGMENTS AND METHODS 21