DETERMINATION OF GENERIC TYPES, ETC. 17 



THE AMERICAN ORNITHOLOGISTS' UNION CODE, 1886, 1892. 



The American Ornithologists' Union Code (1886, 1892, 42-M) treats 

 generic types as follows: 



CANON XX. When a genus is subdivided the original name of the genus is to be 

 etained for that portion of it which contained the original type of the genus when 

 this can be ascertained. 



Remark. This principle is universally conceded and requires no special comment. 



CANON XXI. When no type is clearly indicated the author who first subdivides a 

 genus may restrict the original name to such part of it as he may judge advisable, 

 and such assignment shall not be subject to subsequent modification. 



Remarks. This, in substance, is the rule promulgated by the B. A. Committee in 

 1842, and it has been reiterated in most subsequent nomenclatural codes. Its pro- 

 priety is perfectly apparent, and, as regards the future, no trouble need arise under it. 

 It has happened, however, in the subdivision of comprehensive genera of Linnaeus 

 and other early authors that most perplexing complications have arisen, successive 

 authors having removed one species after another as types or elements of new genera 

 till each of the species included in the original genus has received a new generic 

 designation, while the old generic name, if not lost sight of, has come to be applied 

 to species unknown to the author of the original genus! This, of course, is obviously 

 and radically wrong. 



******* 



CANON XXII. In no case should the name be transferred to a group containing 

 none of the species originally included in the genus. ' 



Remark. This rule is in strict accordance with the B. A. Code and with current 

 usage. 



CANON XXIII. If, however, the genus contains both exotic and nonexotic 

 species from the standpoint of the original author and the generic term is one 

 originally applied by the ancient Greeks or Romans, the process of elimination is to 

 be restricted to the nonexotic species. 



Remarks. The purpose of this restriction in the application of the "principle of 

 elimination" is to prevent the palpable impropriety of the transference of an ancient 

 Greek or Latin name to species unknown to the ancients. By the unrestricted 

 action of the principle of elimination the genus Tetrao, for example, becomes trans- 

 ferred to an American species, viz, Tetrao phasianellus of Linnaeus, the transference 

 being in itself not only undesirable, but, as it happens, subversive of currently 

 accepted names. The working of the proposed modification of the principle of 

 elimination may be thus illustrated. 



The genus letrao Linn., 1758, contains the following: 



Nonexotic species. 

 1. urogallus ( Urogall.us Flem., 1822). 



Exotic species. 



3. canadensis. 

 5. phasianellus. 



2. tetrix. 



4. lagopus (Lagopus Briss., 1760). 

 7. bonasia (Bonasia Steph., 1819, plus 

 Bon., 1828). 



This leaves tetrix as the type of the genus Tetrao, since Lyrurus Sw. was not 

 established for it till 1831. 



On the other hand, the process of unrestricted elimination would result as follows: 



1. urogallus ( Urogallus Flem., 1822). 



2. tetrix (Lyrurus Sw., 1831). 



3. canadensis (Canace Reich., 1852). 



4. lagopus (Lagopus Briss., 1760). 



5. phasianellus (Pediocsetes Bd., 1858). 



6. cupido (TympanuchusGlog., 1842; Cupidonia Reich., 1850). 



7. bonasia (Bonasia Steph., 1819, plus Bon., 1828). 



6328 No. 7905 2 



