







PEEFATOEY NOTE. 



S IN the first volume, which relates to the Mammalia, this, the second volume, 

 contains a "Compendium of Generic Distinctions," by the use of which the 

 classification and nomenclature of the birds of the world can be understood. 

 A general definition is given, showing what a bird is as distinguished from 

 other classes of animals. This explanation is in terms principally implying facts, and is 

 therefore good for all time; though some modification of the language is even now 

 admissible. For example, the sentence "Mouth modified into a horny beak without 

 teeth," must now read "Mouth modified into a horny beak, which in living species has, 

 no teeth ; some extinct forms being provided with true teeth." 



Prof. Marsh's notable discovery of the latter, thus presents an additional character 

 which must enter into the estimate of -fl^at constitutes a bird. 



The fossil Moas, those great birds from New Zealand, skeletons of which measure 

 fifteen feet in one species, have no wings, the hind limbs being so largely developed, organs 

 of flight are wholly unnecessary. 



As the Science of Ornithology stood a quarter of a century since the author's Com- 

 pendium represented the then accepted classification. But many changes have been found 

 necessary from the rapid development of the science witnessed, especially during the last 

 decade. 



As our supervision relates to the species found in North America, we have adopted the 

 classification which has the approval of American Ornithologists, that embraced by the 

 Bulletin of the Smithsonian Institution, prepared by Mr. Ridgway, and entitled : "Nomen- 

 clature of North American Birds." 



We would here return sincere thanks for the courtesy often in past years extended to us 



Vol. II. iii 



