746 TERM ASO SLES, 
Grues (pt.), Pterocles, Alcedinidxe, Momotidxe, Todidx, 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 Ratitx, Spheniscr, 
Colymbus, Podicipes, Steganopodes, Ciconiidx, Plataleidx, Phwnicopterus, 
ee CoLumMBA Livia. Ventral and dorsal aspect. 
(After Nitzsch.) 
Anseres, Palamedea, Dicholophus, Otis tarda (not O. tetrax), Eupodotis, 
Eurypyga, Podica, Rhynchea, 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 pteryle colli laterales, 
divided by a very broad dorsal and a ventral cervical apteriwm, occur 
only in the Herons and in Otis tetraz. 
4, Wing-tract (pt. alaris), composed of the RemicES 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 
