XII THE COLOURS OF BIRDS 251 



fish fat (cf. the statement as to the flamingo 

 above). 



The Pigments of Birds, their Characters 

 AND Distribution 



As to the details connected with the pigments of 

 birds, we may notice first that practically nothing is 

 known of the melanin pigments. They are widely, 

 perhaps universally, distributed in birds, give rise 

 to all the dull and sober tints, colour all feathers 

 displaying any beauty of marking, and are usually 

 associated with feathers displaying structural colour. 

 In birds as in mammals they form the groundwork 

 of the coloration. Of their characters little is known. 

 They may possibly be the same as the dark pig- 

 ments of mammals ; an origin from haemoglobin has 

 been suggested here as elsewhere in Vertebrates, but 

 is not supported by very cogent evidence. 



The lipochromes are numerous and diverse, and 

 have been chiefly investigated by Krukenberg. 

 The most familiar is probably the red pigment, 

 called by Bogdanow zoonerythrin, and by Wurm 

 tetronerythrin, which colours the red feathers of the 

 flamingo {PhcBnicopterus antiquoruni), of the cardinal 

 bird {Cardinalis virginianus), and of many others, 

 the red wattles in the male pheasant, etc. etc. The 

 only other red pigment certainly of lipochrome 

 nature which Krukenberg describes, is one which 

 he calls " araroth," found in the red feathers of 

 certain parrots, and differing only slightly from 

 zoonerythrin. 



Of yellow lipochromes, on the other hand, he 



