42 CODE OF NOMENXLATURE. 



groups and to mike their definitions continually more restricted. In carry- 

 in"; out tills process, it is an act of justice to the original author, that his 

 generic name siiould never be hjst sii;lit of; and it is no less [even more] 

 essentia) to the welfare of the science, that all which is sound in its nomen- 

 clnturc should remain unaltered amid the additions which are continually 

 being made to it." {B. A. Code, 1S42.) 



Canon XX. When a genus is subdivided, the original name 

 of the g^nus is to be retained for that portion of it which con- 

 tained the original type of the genus, when this can be ascer- 

 tained. 



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 promulQ;atcd by the B. A. Com- 

 mittee in 1S42, and it has been reiterated in most subsequent nomenclalural 

 codes. Its propriety is perfectly apparent, and, as re:j;ards the future, no 

 trouble need arise under it. It has hnppeued, however, in the subdi- 

 vision of comprehensive genera of Linnceus and other early authors, that 

 most perplexing complications have arisen, successive authors having re- 

 moved one species after anoUier, 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. 



The B. A. Committee suggests that, when authors omit to specify a type, 

 "it may still in many cases be correctly inferred that theyfrj'/ species men- 

 tioned on their list, if found accurately to agree with their definition, was 

 regarded l)y them as the type. A specific name or its synonyms will also 

 often serve to point out the particular species which by implication must be 

 regarded as the original type of a genus. In such cases we are justified in 

 restoring the name of the old genus to its typical signification, even when 

 later authors have done otherwise." De CandoUe would restrict the old 

 generic name, when no type is specified, to the oldest, best known, or most 

 characteristic of the species originally included in the genus ; or to that sec- 

 tion of the old genus most numerously represented in species. 



As Dall observes, " It would, manifestly, be liable to introduce errors and 

 confusion, if it were insisted that the first species should invariably be taken 



