290 Dr. H. Eltringham on 



made some five hundred carefully mounted preparations 

 of Acraea genitalia, as I had to do for my monograph of 

 the genus, he would, I am sure, agree entirely with my 

 statement. 



At this point Professor Houlbert makes a curious error 

 in quoting my words. In referring to Schatz and Rober's 

 efforts to classify the species of Acraea, I stated that the 

 " characters given are for the most part inconstant." 

 These words Professor Houlbert makes to be my criticism 

 of Mabille instead of Schatz and Rober. It is true I said 

 almost the same thing of Mabille's characters. The words 

 are : " the impossibility of these groups is evident from the 

 instability of the characters suggested." My meaning 

 here was, however, slightly different. Mabille named one 

 of his groups Aphanopeltis, and his characteristic for this 

 group was that the ventral plate of the male armature 

 was a structure of variable form. It did not seem to me 

 that variability, or as I said, instability, could be regarded 

 as a suitable characteristic on which to found a subgenus. 

 Moreover, the features Mabille selected for his classifica- 

 tion are not features of a comparable kind, since in some 

 species they do not occur at all. Finally, his attempt 

 suffers from the great objection that it utilises a purely 

 sexual characteristic as a feature on which to base a 

 classification. 



Now, whether applying to Mabille or to Schatz and Rober, 

 Professor Houlbert objects to my words " the characters 

 given are for the most part inconstant," and says, " mais, 

 ou trouve-t-on des characteres constants ? " Naturally I 

 agree with him that characters are not constant in the 

 absolute sense of the word. Were they so the whole majestic 

 scheme of evolution would be an impossibility. Neverthe- 

 less, there are characters which are relatively sufficiently 

 constant to enable us to use them as a basis for classifica- 

 tion, and when I spoke of the inconstancy of Schatz and 

 Rober's characters I indicated that they were devoid even 

 of that relative constancy which was necessary if they 

 were to be of any taxonomic value. I have nothing but 

 admiration for the descriptions and excellent drawings 

 of the armatures of A. igati and A. damn. As a study in 

 the anatomy of these insects they are admirable. In a 

 footnote on p. 145 Professor Houlbert says, " Mr. H. 

 Eltringham, I.e. p. 7, a donne de ces organes, deux petites 

 schemas trop simplifies (fig. 11 et 12) qui ne peuvent fournir 



