INTRODUCTIOX xix 



in this respect that it is extremely difficult, if 

 not impossible, to tell them apart." From an 

 examination of the osseous structure of both, I am 

 convinced of the justice of Huxley's surmise that 

 Swifts would be found some day to be nothing 

 more than profoundly modified Swallows, having 

 no more affinity with the Humming-birds than 

 these latter. 



Having regard, then, to the diversity of opinion 

 existing with respect to Classification, I see no 

 advantage to be derived by departing from that 

 adopted in the former edition of this " Handbook." 

 This, as above shown, has met with such general 

 approval that I have only so far modified it as to 

 mark the separation of the Passeres from the 

 Picariae by placing them in separate Orders, yet 

 so as to bring the families Hirundinidse and 

 Cypselidse close together, the latter being followed 

 (as in the former edition) by the Caprimidgidae. 

 A further modification will be noticed in bringing 

 together the Cranes and Bustards in the Order 

 Alectorides (as seems warranted by a more com- 

 plete acquaintance with their structure and habits, 

 their mode of nidification, and the resemblance of 

 their eggs and young), the inclusion of the Ibis, 

 Spoonbill, Storks, and Herons in one and the 

 same Order Herodiones, and the separation of the 

 Petrels (Tubinares) from the Terns, Gulls, and 

 Skuas. 



In regard to the subject of Nomenclature, it 



