24<j [November, 



THE BUTTERFLIES OF THE OXFORD DISTRICT. 

 BY JAMES J. WALKER, M.A., R.]S\, F.L.S. 



The Viiried geological formation of the countiy immediately 

 adjacent to Oxford, and its rich flora and extensive tracts of woodland, 

 some of them dating from very ancient times, are eminently favourable 

 to butt<3rfly-life ; while the number of able resident collectors and 

 observers, as well as the constant succession of enthusiastic young 

 entomologists supjilied by the Univei-sity up to the commencement of 

 the present war, has ensured its being one of the most thoroughly 

 worked districts in the British Islands. Unfortunately the only fairly 

 complete list of the local Lepidoptera, published in the Report of the 

 Ashmolean Xatui-al Histor}"" Society for 1898, gives no details beyond 

 the initials of the captor or observer of each species ; but I found it of 

 much serv^ice when, in 1912, I compiled a sketch of the insect fauna 

 of the Oxford district for the use of the guide-book issued to the 

 members of the International Congress of Entomology held here in 

 that year, and of this the present paper, as far as the Rhopalocera are 

 concerned, may be regarded as a reproduction, amplified and brought up 

 to date where requisite. The list of Lepidopte'ra in the Victoria County 

 History of Berkshii-e (1905), mainly compiled by Messrs. A. H. Hamm 

 and W. Holland, though dealing with only a portion of the district, has 

 also been of very material assistance in compiling these notes. 



Of our 67 species of butterflies regarded as tinily British, we now 

 have definite records of 41 as having been observed in recent times 

 within a radius of 10 miles from Carfax, the centre of Oxford, in 

 addition to two or thi-ee species which may have formerly occurred 

 within these limits. This tract of countr}' is about equally divided by 

 the Isis between the counties of Oxfordshire and Berkshire, and attains 

 its highest elevation, 502 feet, at Shotover Hill, about three miles east 

 of the city. It is well within sight of the beautiful and productive 

 chalk ranges of the Chilterns and the Berkshire Downs, but does not 

 include any portion of either ; though one or two of the characteristic 

 luitterflies of the chalk, as Ar/riades corydon and (possibly) Zizera 

 minima^ have wandered from thence and have established themselves in 

 outlying stations in the District. On the whole, oui' Oxford butterflies 

 appear to hold their own very well from year to year, despite the fact 

 that much of om- old woodland has been drastically thinned out, and in 

 great part replanted with uninteresting and unproductive Conifers. 



Both Pieris hrassicae and P. rapae are of com-se plentiful through- 

 out the district, but, especially the former, vary greatly in that respect 



