8 FRANCIS HEMMING 



the old Code is that which now appears as Article 74, which provides that in the case 

 of any nominal species not based on a holotype any of the syntypes may be selected 

 to be the lectotype of the species. This provision is of outstanding importance, 

 wherever in its absence the interpretation of a nominal species would be either 

 impracticable or at least open to serious doubt. 



In the course of the preparation of the present work it was found in a considerable 

 number of cases that the nominal species which was the type-species of some genus 

 was based on specimens or figures of specimens currently treated subjectively on 

 taxonomic grounds as being referable to more than one species, but no steps had been 

 taken to secure a firm nomenclatorial basis for the interpretation adopted. In 

 these cases the deficiency has now been made good by the selection in the work 

 Annot. lepid. either of one of the syntypes of the species to be its lectotype or of a 

 figure, either provided or cited by the original author, to represent the lectotype. 



(d) Increased emphasis in the revised Code on the need for stability and uniformity in 

 zoological nomenclature 



The revised Code published in 1961 places much greater stress than its predecessor 

 on the need for promoting stability in zoological nomenclature and for avoiding 

 vexatious or confusing name-changing on narrow technical grounds. This new 

 outlook, which is stated in express terms in the Preamble to the revised Code and is 

 apparent also in many of its individual provisions, takes its most practical form in the 

 Article (Article 79) now inserted in the Code for the first time setting out the grant to 

 the Commission of Plenary Powers to suspend the normal operation of the rules in 

 cases in which such action is judged by the Commission to be necessary in the interests 

 of stability and universality in nomenclature. The next following Article (Article 80) 

 also contains a provision of great importance in the present connection ; this prescri- 

 bes that, if a case is submitted to the Commission, existing usage is to be maintained 

 until the decision of the Commission is published. 



In the case of the butterflies there are at the present time some twenty applications 

 pending for action under the Plenary Powers. The great majority of these relate 

 to the names of genera considered to have been based upon misidentified type-species. 

 In accordance with the provisions of Article 80 existing usage has been maintained in 

 the present work in the case of all names, regarding which the Commission has been 

 asked to give relief under the Plenary Powers. In each of these cases full particulars 

 are given as to the situation which would arise if the normal provisions in the Code 

 were to be applied and the action which the Commission has been asked to take under 

 its Plenary Powers. 



III. SCOPE AND ARRANGEMENT 



(a) Compilation of a single world list instead of a series of zoo-geographical faunistic 



lists 



When in the early nineteen-thirties I conceived the idea of writing a book on the 



generic names of the butterflies, my idea was to divide the task into two portions, the 



first dealing with the names of genera occurring in the Temperate portion of the 



