130 THE JOURNAL OF EOTANT 



(8) The treatment as homonyms, under the Code, of names 

 which are regarded as different under the Kules, e. g. Chamissoa and 

 Chamissonia ; Lomatia and Lomatium ; Festuca Kingii and F. 

 Kingiana. 



(4) The recognition as vahd, under the Code, of generic names 

 published without generic description but with citation of species, 

 e. g., Per^w/?^;« Salisb. 



(o) The recognition, under the Code, of "priority of place." 

 As examj^les SteUnria Linn, is replaced by Alsine Linn. ; and 

 Minor ea Aubl. by Mi ana Aubl. 



(6) The different method of selecting the type-species of a genus. 



(7) The rejection, under the liules, of specific names in Avhich 

 the trivial merely repeats the generic name. (These tautological 

 names may for the sake of brevity be called taidonyms.') 



The first six causes, in so far as they relate to genera, cut both 

 ways. It will be found that most of the " nomina conservanda '' 

 which are valid under the Code, are valid because the prior names are 

 either homonyms or hvponyms. Let us assume, for the sake of 

 argument, that owing to the operation of the six causes the number 

 of name-changes in respect of " uomina conservanda " is reduced 

 from 15,000 to 10,000. If these six causes operating in one direc- 

 tion on the 458 genera included in the list of " nomina conservanda " 

 produce a deduction of 5000 name-changes, may they not be ex])ected 

 to produce an addition of at least as many changes, operating in the 

 reverse direction in the case of the 9149 genera (nearly twenty times 

 as many) not on the list ? Further name-changes are necessitated 

 by specific names which are homonj^ns or tautonyms. 



The question, however, is one of facts, and it is therefore desirable 

 to test the accuracy of my estimate of 15,000. It is obviously 

 impracticable to count the total changes required in all genera. 

 What may be done is to ascertain the approximate number of 

 changes in a large and fairly representative body of genera, and to 

 see how far it agrees with an estimate based on the " nomina con- 

 servanda" in that bod})- of genera. Tlie test which I have applied is 

 to take the whole of the genera included in Britton and Brown's 

 lUui^trated Flora, ed. 2 (1913), and to calculate the ai)proximate 

 number of name-changes of species required by the American Code. 

 The task has been laborious, but I do not regret having undertaken 

 it, since it has supplied a basis of facts for consideration. It has 

 given some indication of the relative importance of the various causes 

 of difference, and enables us to estimate the effect, for example, 

 of Dr. PennelFs pro])osal to limit " nomina conservanda " to genera 

 containing at least 100 (or 50) species. 



The number of name-changes consequent on the acceptance of 

 the American Code depends of course on the taxonomic basis Avhich 

 is ado])ted, and particularly on the generic concept. There exists in 

 the United States an influential body of systematists, headed by 

 Dr. N. L. Britton, who treat as genera what a majority of botanists 

 at the present time regard as subgenera or sections. As this is 

 purely a taxonomic question, any discussion of it in the present con- 

 nection would be out of place. But it is self-evident that for those 

 who recognize such small genera, the differences in nomenclature 



