298 THE AMERICAN NATURALIST. 
Coefficients of variability have been determined as follows 
for the whole series. 
MALES FEMALES 
SOB GL WANE . 5.5... XUL 2.69 + 
SAME OR Me ge eS ge + 3.65 + 
ween OF D Oe Boa es 689 E 5.35 + 
Depth of bill : Gi. uu o CUT MB Ee 4.61 + 
Melanism of top of head Pao aa s LER d 3.81 + 
Melanism of upper tail coverts . . . . 29.024 39.58 + 
New OF MEUM e e a . a 36548 2832 + 
Curvature of culmen  . . 47 males and females 9.15— 
Florida shrikes were found to have relatively large bills and 
long tails. 
A large percentage of melanism has been found for the top 
of head and the back of shrikes from the south central states, 
while shrikes from the vicinity of Colorado and Arizona have 
a relatively small percentage of melanism for all three color 
surfaces measured. 
I wish to make acknowledgments to Dr. Davenport for 
supervision of the work and helpful criticisms, and to Dr. Mark 
for suggestions and revision of the manuscript. 
CAMBRIDGE, Mass. 
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