PRINCIPLES, CANONS, AND RECOMMENDATIONS. 43 



as the type, or were it permitted to take species subsequently added to the 

 group, and which the original author did not know when he established 

 his genus. No arbitrary rule will suffice to determine, off-hand, questions 

 of so much complication as is often the decision in regard to the type of 

 an ancient genus which has been studied by a number of authors." (Rep., 

 pp. 39, 40.) 



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. 



e> v 



CANOX XXIII. If, however, the genus contains both exotic 

 and non-exotic species, -- from the standpoint of the original 

 author, --and the generic terra is one originally applied by the 

 ancient Greeks or Romans, the process of elimination is to be 

 restricted to the non-exotic species. 



REMARKS. The purpose of this restriction in the application of the ' prin- 

 ciple 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 transferred to an American species, viz., Tetrao phasia- 

 nellus 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 Tetrao Linn., 1758, contains the following 



NON-EXOTIC SPECIES. EXOTIC SPECIES. 



1. urogallus (Urogallus Flem., 1822). 3. canadensis. 



2. tetrix. 5. phasianellus. 

 4. lagopus (Lagopus Briss., 1760). 6. cupido. 



7. bonasia (Bonasia Steph., 1819, -j- 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. lagcpus (Lagopus Briss., 1760) ; 



5. phasianellus (Pcdioccztcs Bd., 1858) ; 



