90 Colouration in Animals and Plants. 



bone, instead of to the dorsal region, as might be expected ; and to 

 brace the wings back a strong furculum the merry-thought is 

 attached. The breast, then, is the seat of the greatest functional 

 activity in birds, and, consequently, we find in a vast number of 

 birds that the breast is the seat of vivid colour. 



As many birds are modified for protective purposes, the brightest 

 species were selected to test our views, namely, the Birds of 

 Paradise (Paradisea), Humming Birds (Trochilidas), and Sun Birds 

 (Nectarinidae). In these birds it is clear that colour has had full 

 sway, untramelled by any necessity for modification. 



Nothing is more striking than the mapping out of the surface of 

 these birds into regions of colour, and these regions are always 

 bounded by structural lines. 



Take, for instance, Paradisea regia. In this bird we find the 

 following regions mapped in colour: 



Sternum ... ... brown. 



Clavicle ... ... yellow. 



Pelvis ... ... yellow. 



Band ... ... brown. 



Frontal bone ... ... black. 



Parutal bones ... ... green. 



Occiput ... ... yellow. 



A beautiful ruff emphasizes the pectoral muscles, and the tail 

 appendages emphasize the share-like caudal vertebrae. 



If we turn to the other species of this genus, we find in P. Papuana 

 the claret breast suddenly change to green at the furculum ; and 

 similar changes take place in P. speciosa, while in P. Wallacei and 

 Wilsoni this region is decorated with a wonderful apron of metallic 

 green. 



The region of the furculum is equally well marked in the Toucans 

 and Sun-birds. 



If now we observe the back of a bird, and view the skeleton with 

 the wings at rest, we shall find it falls into three morphological 

 tracts. First, the shoulder, or scapular track ; second, the thigh, or 

 pelvic ; third, the tail, or caudal region ; and in all these birds the 

 several tracts are beautifully marked by sudden and contrasted 

 change of colour. In P. Wilsoni all the tracts are brilliant red, but 

 they are separated by jet-black borders. In Nectarinea chloropygia 

 the scapular region is red, the pelvic yellow, and the caudal green. 



