196 BIRDS—LAWS OF VARIATION. 
atmosphere and high latitudes, as well as the converse, suggests that 
there may be laws governing variation between the members of higher 
groups similar to those which he considers as varietal. He says: 
‘‘Whatever may be the cause of the above modifications of structure and color, at 
different localities, we certainly find the following coincidences : 
‘ist. In accordance with the increase in the intensity of color in individuals of the 
same species from the north southward, in the northern hemisphere, the brighter colored 
species in general represented in both the temperate and tropical regions occur, as a 
general rule, at the southward; the same fact holding good also for sub-families. In 
cosmopolitan genera, families, etc., the tropical species are almost always brighter col- 
ored than the extra-tropical ones. All the most gorgeously colored families of birds are 
either exclusively tropical or semi-tropical, with generally the outlying species mere 
plainly colored than the average for the family. 
2d. In accordance with the increase in the size of the bill at the southward, all the 
species that have this member enormously developed are tropical or semi-tropical; not 
only such families as have the beak at its maximum of development, as the toucans and 
hornbills, but in all groups in which it is unusually large, the extreme development is 
reached in the inter-tropical regions. 
‘¢3d. In respect to the tail, with very few exceptions, all long-tailed forms reach 
their highest development within or near the equatorial regions. 
“The facts indicated above in respect to the inosculation of forms formerly regarded 
as specifically differentiated will evidently require modifications of the hitherto ac- 
cepted nomenclature. Evidently, many of these forms are so strongly marked that 
they should be, in some manner, recognized in nomenclature, though admittedly of less 
than specific rank. Most naturalists now practically recognize as species such groups of 
individuals as are not known to graduate by nearly imperceptible stages into any other 
similar group, and as varieties such groups of individuals as occur at certain localities, 
or over certain areas, which differ more or less from other groups inhabiting other (gen- 
erally contiguous) localities, with which there is evidence that they do more or less fully 
intergrade. Convenience seems to demand such a course, in order to enable the natu- 
ralist to specify what particular variety or race of a species inhabits a given section of 
country: a method, in fact, already more or less generally practiced.” 
As the State of Ohio presents no marked elevations of surface and its 
area is too limited to admit of any marked geographical variation in spe- 
cies, | have found it interesting to follow the suggestions contained in 
the concluding paragraphs above quoted, and have compared our resi- 
dent and summer resident birds with migrants, as regards the variation 
in those of a similar type or pattern of coloration. This comparison 
and its results, in which I attempt to show that southern species (tesi- 
dents and summer residents) differ from northern species (migrants and 
winter visitors) in being more highly developed in coloration and pat- 
tern of plumage, northern birds remaining in a condition, in these re- 
spects, resembling the young of the southern forms, was made the sub- 
ject of a paper read before the Columbus Natural History Society, August 
29,1874. This paper will be found in the appendix to this report. 
