1914] Beebe: Preliminary Pheasant Studies. 277 



single pair of central, superior, disintegrated tail feathers, show- 

 ing that the locus of specialization is the same as in the other 

 species. 



In the presence or absence of certain rectrices in these birds 

 we encounter another of those unexpected correlations which 

 meets the student of avian evolution at every step. As regards 

 color there is no doubt but that the snow-white tibetanum birds 

 are by far the more specialized. White is always an extreme 

 achievement in pigment radiation or rather elimination, and 

 their colored young show how recently the adult hue has been 

 acquired. But on the other hand, the greater number of four 

 and twenty tail feathers in the blue-gray auritum is in its way, 

 as extreme a specialization — excelled in the family Phasianidae 

 only by the adult Lobiophasis. Thus the complexity of evolution 

 is forever being impressed upon us — specialization correlated 

 with generalization and vice versa in closely related organisms. 

 Only by the sum total — the balance after the intricate addition 

 and subtraction of all its character units, and even then only 

 by visualizing the genealogy in three planes of space — can we 

 ever hope successfully to orient any species in relation to its 

 predecessors and contemporaries. 



Genus Gennaeus. 



Along the southern slopes of the Himalayas as well as in 

 Burma, Yunnan, China and elsewhere I obtained an unusually 

 complete collection of these interesting and puzzling birds, and 

 especially a series of immature and moulting individuals, some 

 of which prove beyond question that hybridization has had much 

 to do with the excessive variation, which has given cause for 

 the making of almost forty species. 



Unfortunately I was obliged to postpone my desire to ex- 

 amine the Gates' collection of Gennaeus in the British Museum, 

 which contains fourteen or fifteen types. Published descrip- 

 tions of these birds are, on the whole, so meagre as to lesser de- 

 tails, and based in many instances on such exceedingly super- 

 ficial diagnosis that I do not feel justified in publishing a sum- 

 mary of my observations until such time as the accessibility of 

 the types to visiting ornithologists will provide data on which 

 to base definite and final conclusions. 



