198 CHARACTERISTICS OF WARBLERS 



diverse, other forms are observed to melt insensibly into each 

 other ; so that, taken altogether, the supposed families are in- 

 separable. This state of the case is admitted by the best 

 authorities, who nevertheless continue to follow usage, as I do 

 in the present instance, partly for the sake of convenience, 

 partly because it is not yet clear what else to do. As I re- 

 marked some years ago, " it is probable that final critical study 

 will result in a remapping of the whole group " of these allied 

 nine-primaried American Oscines; and I might have added, 

 that such course is urgently demanded. 



Nevertheless, it is practically an easy matter to recognize 

 any North American example of this arbitrary group — the dif- 

 ficulty is with its limitation, not within its ascribed boundaries. 

 All the " Sylvicolines" are small birds ; excepting the species of 

 Icteria, and perhaps of SiuruSj none are over six inches long, 

 and the mean length is even less than this. The usual or nor- 

 mal shape of the bill is that of an elongate compressed conoid, 

 but its variations in details of configuration are great; in Icteria 

 it is very stout and high, and in Setophaga broad and flat, like a 

 Flycatcher's. The bill is usually nicked near the end, sometimes 

 not; sometimes strongly notched and hooked, though not also 

 toothed as in Vireonidce — more as in Tyrannidce. The rictus 

 is usually bristled; sometimes not ; sometimes the bristles are 

 very highly developed, much as in Tyrannidce. The wings are 

 longer than the tail, and more or less pointed, excepting in 

 Geothlypis and Icteria. The feet show some minor, though very 

 evident, modifications, in adaptation to the scansorial habits of 

 some genera, and the terrestrial habits of others. 



This is the second largest family of North American birds, 

 the Fringillidce alone surpassing it in number of species. If 

 not exactly "representative", in a technical sense, of the Old 

 World Sylviidcc, it may be considered to replace that family in 

 America, having much the same role in bird-economy: both 

 families abound in species and individuals; they are small, 

 migratory, insectivorous, and everywhere take prominent part 

 in the make-up of the bird-fauna. There are ui)ward of a hun- 

 dred species of Sylvicolidcc, distributed over the whole of North 

 and Middle America, and much of South America. The centre 

 of abundance of the Setojphaginw, or Flycatching Warblers, is 

 in the warmer parts of America; comparatively few species 

 reach the United States, and only two or three are extensively 

 dispersed in this country. On the other hand, the Sylvicolince 

 are more particularly birds of North America; very few of 



