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TH RLLTO17S OF WEIGHTS, BODY DIMENIONS, AND SEX Aldo epl Sinc 1 I have recorded the weights of some 600 6noks of fifteen species killed mostly in the upper Rio Grande Valley of New Mexico. The seasonal variations in l*eights and their apparent relation to 2plumage changes have been described in previous papers. It occurred to me that duck hunters have a further opportunity of contributing to ornithology by determining the interrelations of weight and various body measurements. Ac- cordingly, ea body measurements were taken on 23 mallards killed during December, 1922, October and Deoember, 1923, and January, 1924, at various points in the upper Rio Grande Valley of New Mexicb, and on 21 mallards killed in Henderson County, Illinois, November 5-7, 1925. All these birds were weightd on the same scales, but unfortunately the body measurements, with the exoeption of bill and length, are not comparable throughout. In the New Mexico birds, spread was taken; in IlUiois the standard wing measurement. Length of foot was taken in New Mexico, but not in Illinois. This lack of standardization prevented complete statistical analysis of the non-standardiz- *&:Admensions. "Notes on the weights & plumage of ducks in New Mexico" Condor XX, Mayo 1919, pp.128-129. 2 "Weights & plumage of ducks in the Rio Grande Valley", Condor , May, 1921, pp. 85-86.*