PTERYLOSIS 747 
humerus, and with the SCAPULARS forming a narrow band across 
the upper arm parallel to the shoulder-blade. 
7. Femoral or Lumbar tract (pt. femoralis s. lumbalis), forming 
an oblique band on the outer side of the thigh. 
_ 8. Crural tract (pt. cruralis), clothing the legs so far as they 
are feathered. 
9. Head-tract (pt. capitis), that which covers the head. 
Remarkable and of rare occurrence is a well-defined occipital 
apterium as is seen in Colius and Trochilide. 
10. Tract of the OIL-GLAND (pf. wropygii). 
The description of the Pterylosis of any bird is not exhausted 
by an enumeration of the 
pterylex and apteria, but should 
also include the disposition of 
Downs, other than POWDER- 
Downs, both in the young 
and the old. The distribution 
of Downs on the featherless 
spaces as well as among the 
contour-feathers is a primary 
feature, and is characteristic 
of the following— Accipitres, 
Alcidx, Anseres, Cathartide, 
Ciconiide, Colymbidxe, Dicho- 
lophus,  Eurypyga, Gruide, 
Laridx, Opisthocomus,  Pala- 
medea, Phanicopterus, Plata- 
leidxe,  Podica, Podicipedide, 
Psittaci, Rallide, Rhinochetus, 
Sphenisci, Steganopodes, Tubin- 
ares—curiously also in Cinclus 
and in the aquatic members 
of the Alcedinide.  Restric- 
tion of Downs to the apteria GEcINUS virIDIS. Dorsal aspect. 
is found in the adults of 
Ardeidx, Caprimulgidx, Cypselidx, Cuculidex, Gallinx, Otididx, Passeres 
(except Cinclus), Pteroclidx, Scopus, Striges and Turnicide. In 
the Tinami only are Downs confined to the pterylx ; but in them 
they are sparsely and frequently thinly developed, as is also the 
case with the Cuculidx, Dicholophus, Gallinx, Limicolx, Opisthocomus, 
Pteroclidxe, Turnicide and some Passeres, while they are wholly 
absent in Africhia, Bucerotidy, Capitonide, Coliidx, Columbide, 
Coraciide, Eurylemide, Galbulide, Menura, Meropidide, Momotide, 
Picidx, Ratitx, Rhamphastide, Todidex, Trochilide, Trogonidx, Upupide 
and in most Passeres. 
