No. 412.) SMALLER NORTH-AMERICAN SHRIKES. 295 
It was impossible to get as accurate results in the second 
series, because of greater difficulty in determining the-actual 
point of tangency, but the results obtained show that there is 
a fairly close correlation in the curvature for various parts of 
the bill; that is, where the culmen is much curved in one 
place, it is likely to have correspondingly strong curvature at 
other points. 
The only selection exercised in the whole work was employed 
in the estimation of curvature, individuals which appeared on 
inspection to be typical for their respective subprovinces having 
been chosen, since it was impossible, for want of time, to photo- 
graph the entire series. 
C. Discussion of Results and Conclusions. 
Although computations have been carried out to the third 
or fourth decimal place, figures beyond the second decimal 
place are not given, as they would imply a degree of precision 
which is not attainable in an investigation of this kind. For 
example, the mean length of wing for 168 male shrikes is seen 
to be (see Table VI) 99.09 -4- mm. It often happened in mak- 
ing correlations that, because of general wear or some special 
mutilation to a single character, some individuals could not be 
included in a correlation table. This has happened especially 
often in the case of the tail, so that in the correlation table for 
wings and tails only 140 of the 168 male shrikes could be 
included. The mean for the left wings of the series of 140 
shrikes was found to be 99.06 mm. (see Table I), a result 
Which differs from the mean of the whole lot (168) by 3 in 
the second decimal place. 
The modes and means given for the melanism of the breasts 
of Appalachian-subprovince shrikes show a percentage which, 
though higher than in other subprovinces, is not as high as 
Would have been the case had not a large proportion of indi- 
viduals come from localities intermediate between the Campes- 
trian and Appalachian subprovinces.  Shrikes from New 
ngland were found to have 50-60% of melanism for the 
breast. An analysis of material shows that only five skins 
