746 



PTERYLOSIS 



Grues (pt.), Pterocles, Alcedinidw, Momotidse, Todidse, Colii, Trogones, 

 Menura, Atrichia and most Oscines. 



(2) Ventral tract (pt. ventralis). This is nearly as diverse as 

 the foregoing, and is next to it in taxonomic value. It always has 

 a longitudinal median apterium of variable extent, but in Stegano- 

 podes this is only a narrow space extending from the furcula to the 

 vent, while in Ardea each half of the pteryla is but a narrow band. 

 The presence and shape of a lateral pectoral branch is also an 

 important feature. 



(3) Neck-tract (pt. colli). This is unbroken in fiatitte, Sphenisci, 

 Colymbus, Podicipes, Steganopodes, Ciconiidx, Plataleidte, Phcenicopterus, 



COLTJAIBA LIVIA. Ventral and dorsal aspect. 

 (After Nitzsch.) 



Anseres, Palamedea, DicJwlophus, Otis tarda (not 0. tetrax), Eupodotis, 

 Eurypyga, Podica, Eliynchsea, Opisthocomus and Buceros. All other 

 birds have lateral cervical apteria of variable length, sometimes in 

 addition to the median cervical apteria which, whether dorsal or 

 ventral, are often long. What Nitzsch called pterylse colli laterales, 

 divided by a very broad dorsal and a ventral cervical apterium, occur 

 only in the Herons and in Otis tetrax. 



4. Wing-tract (pt. alaris), composed of the REMIGES with their 

 coverts, and hence of great importance. 



5. Tail-tract (pt. caudalis), composed chiefly of the RECTRICES 

 with their upper and lower coverts. 



6. Shoulder-tract (pt. humeralis), always well marked, consist- 

 ing of the feathers, often called tertials, which grow from the 



