XLIV 



The same phenomenon occurs in the Erycinidae. I have already told 

 how, ten years ago, my article " Ucbcr die sogenannie Sc/nvdnze dcr Lcpidoptcra" 

 was the occasion for an attack, equally stupid and conceited, by a German 

 systematist, which displayed in the most blatant manner the total incapacity 

 to which I have often referred, of comprehending the meaning of evolution. 

 On that occasion it appeared that this individual was annoyed with me amongst 

 other things because I denied his assertion, that the pupae of the American 

 Erycinidae-genus Stalachtis, were fastened without a girdle thread, merely as 

 suspensi. He had taken this from W. W. Bates, who it row appeared had 

 not observed it himself And what did I discover through further investigation ? 

 The pupa of one species of this genus is reproduced in the old work of Sepp, 

 Surinaamsc/u Insektcn without a girdle thread, but in the French and Dutch 

 text belonging to it, it is distinctly stated that it is attached by a girdle thread. 

 Moreover, in looking up the original drawing, still extant in the library of 

 the Ned. Ent. Vereeniging, I found that the girdle thread was there repre- 

 sented ! It had therefore been omitted in the colouring of the plates in the 

 above mentioned work ; presumably owing to the difficulty of reproducing 

 it with sufficient fineness. Thus the erroneous picture had become a scientific 

 fact ; the French and Dutch text was problaby not consulted by those who 

 could not understand it. In this way we see how errors may arise, and that 

 therefore accurate observations are necessary. Another fact is the following. 

 When I had caught a caterpillar of the Javanese Erycinida Zemeros Flegyas 

 Cram, for the first time, it turned into a pupa upon a leaf, the chrysalis, 

 as it seemed to me, being attached only to the cremaster, not by a girdle 

 thread, which at the time surprised me very much. Subsequently I obtained 

 more of these pupae, and observed that they did possess a girdle thread, 

 although a very thin one. How did this happen? Did I make a mistake the 

 first time? That is not very likely, I had good eyes then, and was in the 

 habit of observing Lycaenidae-pupae ; the absence of the thread surprised me 

 very much at the time. Or is the girdle thread present in some individuals, 

 while it has disappeared in others ? Does the fact that in the former case it is 

 so very fine, indicate that it is to be considered as a phase in the process of 

 disappearance? This is quite possible, and if so, it would be yet another 

 striking example of the gradual and uneven character of evolutionary changes. 



I must now point out a few inaccuracies which have crept into my last 

 monograph. On p. 51, there are named, and on Plate XVI fig. j6ab a 

 drawing is given of two specimens of Ypthima Argillosa Sn. This species must 

 be cancelled. Fruhstorfer drew my attention to the fact that these drawings 



