﻿EXTERNAL ANATOMY. — MIGRATION. 97 



tion, we may notice the very singularly formed wing of 

 the Cape honeysucker (Ptiloturus), distinguished no less 

 for its very long plume-like tail, than for the form of its 

 fifth quill feather, which is suddenly contracted, midway, 

 to about half its length : and although the third and 

 fourth have a slight indication of the same structure, 

 the sixth is of the ordinary shape. We have drawn 

 the attention of the ornithologist to these instances of 

 unusual structure, because they have never been pointed 

 out ; and several others could be mentioned ; but, as 

 we are unacquainted with their influence on the habits 

 and economy of the birds, the enumeration might be 

 tedious. 



(87.) Migration is performed by the wings ; but 

 as this subject is more connected with the habits and 

 instincts of animals, we shall merely give it, in this 

 treatise, a passing notice in reference to external struc- 

 ture. If there was any particular shape of wing more 

 peculiar than any other to birds which migrate, it would 

 seem to be that which we have designated as acuminated, 

 that is, having the first two or three primaries fully de- 

 veloped. The swallows, in this respect, are pre-eminent, 

 and they are accordingly both the swiftest and the most 

 distant migrators. Next to these are the bee-eaters, the 

 rollers and the quails, which come from the shores of 

 Africa in the spring, and after spending the summer in 

 the southern half of Europe, return to their home at the 

 commencement of autumn. Nearly the whole of the 

 American warblers (Sylvicolce), together with the Maize 

 birds (Agelaince), migrate in a similar direction, from 

 south to north, and after breeding in the United States, 

 return and pass the winter in the Mexican Gulf. All 

 these tribes are characterised by having their wings more 

 or less pointed ; a structure peculiarly adapted for such 

 migrations ; but, on the other hand, there are numerous 

 other species which annually perform the very same jour- 

 neys by the aid of wings altogether different. We need 

 only mention the orioles and the hoopoes as companions 

 to the rollers, but whose wings have the three first quills 



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