PREFERENTIAL MATING OF VARIETIES 87 



cases of captured pairs sent to me by correspondents 

 in South Africa, and sometimes in cases of the same kind 

 which occurred to myself when collecting. The species 

 which particularly attracted my notice in this way during 

 my visit to Natal was Hypanis acheloia (= Gotzius* Herbst, 

 part), which is curiously variable on the underside, from 

 pale creamy to deep chocolate. I did not know of its 

 seasonal variation at the time, but I was in Natal just at 

 the change of season from wet to dry, when the inter- 

 mediate gradations were about, and I was struck with 

 the close resemblance of the sexes in pairs that I caught. 

 I am sorry to have nothing more definite to give on this 

 head ; it is a point much requiring exact and prolonged 

 observation.' 



Mr. Trimen furthermore entertains no doubt that much, 

 if not all, of the material upon which he based the con- 

 clusion that the individuals of the same race tend to inter- 

 breed, exists, distinctively labelled, in the South African 

 Museum, at Cape Town. It is greatly to be hoped that 

 collectors will in future carefully label all specimens cap- 

 tured in coitu, and that the fact will be recorded on the 

 labels in museums and in private collections. It is 

 tantalizing to reflect upon the number of interesting and 

 important questions which could be now decided if this 

 practice had prevailed during the past fifty years. The 

 question of the possible origin of species from races by 

 preferential Syngamy is of such high importance that we 

 may confidently hope that the attention here directed 

 to the question, and especially the quotation of Darwin's 

 letters to Bates, may lead to that ' exact and prolonged 

 observation ', accompanied by careful records, without 

 which a safe decision cannot be reached. In the mean- 

 time the decided impressions of two such naturalists 

 as H. W. Bates in South America and Roland Trimen in 

 South Africa render it in every way probable that the 

 conclusion will be established on a firm foundation. 1 It 



1 Dr. T. A. Chapman sends me the following interesting and suggestive 

 note : 



' I met lately with a curious instance that deserves following up, of some 

 bearing on the question of selective mating of varieties. 



