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 whichhe considers as varietal. He says : 



" Whatever may be the cause of the above modifications of structure and color, at 

 different localities, we certaioly find the follovring coincidences : 



" Ist. In accordance with the increase in the intensity of color in individnals of the 

 same species from ttie 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 southwird ; the same fact holding good also for snb-familiea. 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 more 

 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. 



"8d. In respect to the tail, with very few exceptions, all long tailed forms reach 

 their highest development withiu 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, I have found it interesting to follow the suggestions con'ained 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 (resi- 

 dents and summer residents) dififer 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. 



