C. J. tSundevall on the Wings of Birds. 407 



Parus and Passeres). They seem to be longest in Corvus, in 

 which they reach a little over the half of the body^ and 

 shortest in Hirundo and Cei'thia (and probably in many of 

 the short-winged tropical forms) ^ in which they only reach 

 one third. It must be remarked that precisely those which 

 have the shortest wing-bones are the best and the worst fliers 

 of the whole order. 



Two special osteological conditions cause some alterations 

 in the above-cited measurements^ although these are rarely 

 of much importance. It must be remarked, however, in the 

 first place, that these^ as well as all forms in the skeletal 

 structure of birds^ are subject to many exceptions^ and by no 

 means indicate the affinities of the species with the same 

 certainty as the external feathery covering. This is there- 

 fore noticed rather to give a distinct idea of the constitution 

 and measui-ements of these parts than to furnish definite 

 characters. 



The first relates to the constitution of the shoulder itself. 

 In the Song-birds the os coracoideum is, in general, slender, 

 and projects as a short, somewhat inwardly-directed process 

 in front of the articular surface of the humerus. The 

 humerus is attached at the very front of the trunk, and pro- 

 jects nearly as far forward as the true scapular tubercle (of 

 the OS coracoideum). This bone (humerus) is therefore here 

 but little shorter than the measurement just given, or nearly 

 half the length of the body. In the Water-birds, Waders, 

 Raptorial birds, Gallinse, and in the greater number of the 

 Coccyges, on the contrary, the os coracoideum is generally 

 thicker, and projects as a very large shoulder-tubercle, like 

 a somewhat longer piece of the same bone, right in front of 

 the articular surface of the humerus. The humerus, there- 

 fore, is attached somewhat further behind the shoulder- 

 tubercle, and consequently loses something more of the stated 

 length. Besides this, the great upper edge of the humerus 

 for the attachment of the muscles of the shoulder (repre- 

 senting the tuberc. majus humeri) projects, in the Song-birds, 

 directly outwards horizontally from the articular surface, by 

 which means the humerus stands out strongly transversely 



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