140 THE entomologist's record. 



Collective inquiry as to Progressive Melanism in Moths. — Memo= 

 randum from the Evolution Committee of the Royal Society. 



The committee appointed by the council of the Eoyal Society to 

 promote investigation of facts relating to " variation," " heredity," 

 " selection," and other phenomena connected with evolution are 

 desirous of instituting a collective investigation into the progressive 

 melanism of certain moths, particularly Geometridac. It is well known 

 that in certain districts, especially within the British area, dark forms 

 of several species of moths have recently appeared and become increas- 

 ingly abundant. There is reason to believe that these dark forms are 

 in some cases extending into other districts and even to the European 

 continent. It is to be regretted that no systematic or statistical records 

 of these phenomena have been kept, and it appears to the committee 

 that if such a record be now instituted and continued for a period of 

 years it cannot fail to have considerable scientific importance. The 

 matter is one that may conveniently be made the subject of collective 

 investigation, and the committee will be glad to hear from any ento- 

 mologist who may be willing to contribute now, or hereafter, particulars 

 as to the condition of these species in the district or districts with 

 which he is personally familiar. The returns should relate as far as 

 possible to specimens found in a wild state, whether as imagines, or 

 pupae, larvffi, or eggs. Information respecting specimens bred from 

 wild parents must be kept distinct. It is thought desirable that the 

 enquiry should for the present be confined to the following species : 



AcidaUa aversata, Amphidasys hcUdaria, Boarniia rcpandata, 

 Camptogramma bilineata, Gnophos obscurata, Hemeropkila abruptaria, 

 Hybernia j^rof/emmaria, PJiiyalio pilosaria, Acronycta pm, Ayroth corticea, 

 Aplccta nebulosa, Polia eld, Vennsia cambrica, XylopJiasia polyodon. 



The schedule in which it is suggested that the returns should be 

 made is termed Schedule A. It is desired that the return for each 

 species be made on a separate schedule, and the secretary will be glad 

 to furnish a supply of these schedules to any one who may be willing 

 to assist. Since confirmatory evidence is of especial value, the 

 committee are desirous of receiving returns made independently by 

 different persons for the same district. It is of course hoped that 

 returns may be obtained for districts in which the dark forms are 

 still unknown. The secretary will be glad to examine and prepare, 

 descriptions of any illustrative specimens lent to him for that purpose, 

 and in suitable cases arrangements will be made for photographing 

 such specimens. 



Historical Evidence. — As the changes in question have largely 

 taken place within living memory, it is hoped that those who have 

 personal knowledge of the facts may be induced to put them on record 

 in such detail as is still possible. Much information of a historical 

 character is of course already printed in the scientific journals, but a 

 more detailed account of the facts would be of great value. With this 

 object a special schedule (B) marked " Historical " will be issued to 

 those who will fill it up. 



On publication full acknowledgment will be made of all help 

 received. All communications should be addressed to the Secretary of 

 the Evolution Committee, W. Bateson, Esq., F.R.S., Merton House,. 

 Grantchester, Cambridge. — May, 1900. 



Errata. — p. 109, line 1, for "first" read "post"; line 2, for " free " read 

 " pre"(-spiracular). 



