PTERYLOSIS 



7A7 



humerus, and with the Scapulars forming a narrow band across 

 the upper arm parallel to the shoulder-blade. 



7. Femoral or Lumbar tract (jpt. femoralis s. lumhalis), forming 

 an oblique band on the outer side of the thigh. 



8. Crural tract (j)t. cruralis), clothing the legs so far as they 

 are feathered. 



9. Head -tract (j)f. capitis), that which covers the head. 

 Remarkable and of rare occurrence is a well-defined occipital 

 apterium as is seen in Colius and Trochilidx. 



10. Tract of the Oil-gland {pt. tiropi/gii). 



The description of the Pterylosis of any bird is not exhausted 

 by an enumeration of the 

 pterylm 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, Cathartidai, 

 Ciconiidx, Colymbidse, Dicho- 

 lophus, Eurypi/ga, Grimlai, 

 Laridx, OpistJwcomus, Pala- 

 medea, Phcenicopterus, Plata- 

 leidx, Podica, Podicipedidx, 

 Psittaci, Ballidx, Phinochetvs, 

 Sphenisci, Steganopodes, Tuhin- 

 ares — curiously also in Cinclus 

 and in the aquatic members 

 of the Alredinidce. Restric- 

 tion of Downs to the apteria, 

 is found in the adults of 

 Ardeidse, Caprimulgidse, Cypselidaj, Cuctdidx, Gallinse, Otididse, Passeres 

 (except Cinclus), Pteroclida}, Scopus, Striges and Turnicida}. In 

 the Tinami only are Downs confined to the pten/lie ; but in them 

 they are sparsely and frequently thinly developed, as is also the 

 case with the Cuculidce, Dicholoplms, Gallinm, Limicola}, Opisfhocomus, 

 Pteroclidai, Turnicidx and some Passeres, while they are wholly 

 absent in Atrichia, Bucerotidai, Capitonidai, Coliidai, Golmnhidai, 

 Coraciidx, Eurylaimidx, Galhulidx, Menura, Meropididx, Momotidm, 

 Picidse, Eatitie, Pihamphastidm, Todidai, Trochilidse, Trogonidx, Upupidai 

 and in most Passeres. 



Gecinqs viridis. Dorsal aspect. 



