(> BULLETIISr 50, UNITED STATES NATIONAL MUSEUM. 



The Pterocletcs ag-roe Avith the Cohunbie in rudimentary vomer; with 

 Laro-Limieohe in tracheo-bronchial syrinx, functional caeca, and nidi- 

 fugous. ptilopivdio young; but they possess so many characters not 

 shared l)y either of the other two groups that it is difficult to under- 

 stand why they should not constitute a group equal in taxonomic rank- 

 with that composed of the Limicohv and Lari together.^ 



It is chiefly in matters of this kind wherein the arrangement shown 

 in the following key to the higher groups of Ornithurae diflfers from 

 Dr. (xadow's latest scheme,^ which in the main appears so satisfactory 

 that no deviation from it seems called for. Among the difficulties con- 

 nected with its preparation perhaps the greatest arises from the fact 

 that in most cases groups have ]>een defined by characters not mentioned 

 in the diagnoses of allied groups, thus necessitating a laborious tabula- 

 tion of characters gleaned from all available sources, and rendering 

 the sifting and weighing of evidence extremely difficult and perplexing. ' 



Nothing original is claimed for the classification here given, except 

 as to the form in which it is presented. It is simply the result of an 

 elective process, the evidently good of other systems being retained 

 and the obviously bad rejected, according to the author's ability 

 to correctly interpret the evidence.'* 



^In the Systematischer Thiel of Bronn's Thier-Reichs. Vogel (18^3, pp. 195, 207), 

 Dr. Gadow divides tlie Order Charadriiformes into two series — I, Verband der Lnro- 

 Limkohv, and II, Verband der Ptcrodo-Columhse; but this subdivision is abandoned 

 in his later work. 



^The "Suborders" of Dr. Gadow's scheme are, however, in the following one 

 raised to the rank of Orders. This may seem nnadvisable if, indeed,, not entirely 

 unwarranted from the standpoint of comparative anatomy alone; but it must be 

 evident to most ornithologists that in the Class Aves a different standard of value 

 must be given to the groups from that of other classes of Vertebrates, for, notwith- 

 standing the peculiar uniformity of fundamental structure among birds, the variations 

 of type are certainly not less numerous than in other classes of Vertebrates. As Dr. 

 Gadow truly remarks (Classification of Vertebrata, pp. vi, vii), "Each class has 

 * * * its own standard units, just as one nation reckons with £, s., d., another 

 with dollars and cents, and a third with marks and pfennigs, which again are not 

 the same as francs and centimes," and "it is obvious that a class which consists of 

 more than 10,000 recent species may call for more subdividing than one which com- 

 prises scarcely one-third of that number." 



•'The works which have been most frequently consulted in the preparation of the 

 following " Key to the Orders of the Class Aves," as well as in connection with the 

 higher groups in general, are the following: 



BEnT).\KD, Frank E. The Structure and Classification | of | Birds | l)y | Frank E. 



Beddard, M. A.,F. R. S. | Prosector ami Vice-Secretary of the Zoological Society 



of London | Longmans, Green, and Co. | 39 Paternoster Row, London | New York 



and Bombay | 1898 | . (8™,pi). [i]-xx, 1-548; numerous cuts in text.) 



Cope, E. D.— Synopsis of the Families of Vertebrates. American Naturalist, xxiii, 



Oct., 1889, pp. 849-877 (Aves on pp. 869-873). 

 Ft-RHKixGER, Max. Untersuehungen | zur | Morphologie und Systematik | der | 

 Vogel I Zugleich ein Beitrag zur Anatomie der Stiitz-und Bewegungsorgane | 

 von I Max Fiirl)ringer | o. ;>. Professor der Anatomie und Director des anatom- 



