SECOND PART. 



SPECIAL PTERYLOGRAPHY. 



CHAPTER 1. 

 RAPACIOUS BIRDS ACCIPITRIN^E. 



THE sole general and characteristic condition of the tract-formation in this group, is the 

 furcate division and degradation of the portion of the spinal tract situated between the shoulder- 

 blades, by which it may be distinguished with certainty at least from the Passerines. To this 

 may be added some less characteristic peculiarities, especially the wide separation of the two 

 stems of the inferior tract, and also the emission, by each of them, of an external branch, whicli 

 is usually connected with the main stem only in front. The lumbar tract is but little marked 

 throughout, or is entirely deficient; the crural tract, on the other hand, is just as strongly 

 developed. There are always ten primaries ; and in the spurious wing I have always found four 

 feathers. The number of tail-feathers amounts in most Accipitrinae to twelve, and is never less; 

 some Vultures have fourteen. 



I. DIURNAL RAPACIOUS BIRDS AccipitrincK Diurnce. 



The most important pterylographic characters of these consist in the presence of an aftershaft 

 on the contour- feathers, which is wanting only in Cathartes and Pandion ; in the occurrence of 

 down-feathers among the contour-feathers in the tracts ; and in the presence of a circlet of feathers 

 at the apex of the oil-gland, which, however, singularly enough, does not occur in the Vultures of 

 the New World (Sarcorhamphns and Cathartes). Both in this character, and in the form 

 of the pectoral portion of the inferior tract, these Vultures approach the Owls, especially Hybris 

 flammea ; and the same statement applies to Pandion, which also approaches the Owls in its 

 reversible toe. Between the Vultures of the Old World, those of America, and the Falcons, there 

 are, however, other pterylographic differences of considerable significance. 



A. VULTURES OF THE OLD WORLD. 



The chief pterylographic character of these is, the enormous dilatation of each half of the 

 inferior tract upon the great pectoral muscles into an external branch, which, however, remains 



