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 68 THE CONDOR VoL. XII described as A. phoenceus nelralis, and shows black innermost coverts with some slight tipping and spotting on the others. Now what are we going to call the middle bird from Stanislaus County ? The iIarin County bird has a slightly smaller bill than the other two in this photograph, but many specimens overlap in measure- ments, which i.ntergrade just as much as the coverts in the males and the streakings in the females. (See Fig. 23.) In these tables the principal measurements are the wing and bill measure- ments. While the former is not to be altogether depended upon I have used it to some extent, ,discarding those cases where the primaries seemed to be so badly worn as to be valueless for comparison. I have included the tail, but this was no criterion of any great value, and in the breeding season is generally very badly shortened by wear. The birds from Stanislaus County show a peculiar thickness of the upper Fig. 23. THREE MALES OF A GELAIUS ILLUSTRATIBIG TI-IE VARIATIOBI IN TI-IE MARKIBIGS OF TI-IE LESSER WlBIG COVERTS mandible in most cases, and I have endeavored to show this in the form of a meas- urement by taking the width of the bill at the center of the culmen. In order to do this a little instrument was rigged lp, with a horizontal ring which could be raised or lowered above a plane surface, to which it was parallel, by means of a screw, the ring being adjusted at half of the culmen as each individual was measured, the bill inserted perpendicularly therein and the width taken by means of a parallel ruler, so arranged that the sharp edges faced each other, laid flat on top of the ring with the bill between the thin edges. As the bills of this species vary so greatly this measurement does not exactly express the differences in heaviness it was intended to show, but it helps to give the idea. The depth or width of a bill from base is a difficult matter to obtain correctly in bills that are of such conical shape as in Agelaius, and probably no two persons would get exactly the same figures, but with care they would come very near doing