﻿208 THE ENTOMOLOGIST. 



between the two species consisted in, was that no two specimens seemed 

 exactly alike and that the number of points was very various, and it 

 seemed difficult in so small a number of specimens as that mounted, to feel 

 any security that even more definitely intermediate forms might not 

 occur. 



My careful re-examination of these specimens shows, however, that this 

 process B has a free margin on one side, and that the other side is adherent 

 to the eversible membrane, leaving only the tip free all round. When one 

 regards merely this free tip, then the specimens arrange themselves into 

 ilicis and cbscuH quite satisfactorily. 



Figs. 3, 4, 5 and 6, represent examples of ilicis (from camera sketches), 

 and 7, 8 and 9 of cesculi. The limit of attachment on the attached side 

 is marked in each case. 



It appears that in ilicis the free extremity is much shorter than in 

 cBsculi, the points usually more numerous. In ilicis the free portion close 

 to the attachment is short and has several points, then further out on the 

 free side is a shorter projection with one or more spines. In cesculi there 

 may be, as in fig. 9, one long simple cusp (not unlike acacice). This cttsp 

 may have, as in 7 and 8, subsidiary spines, one or more, on the side facing 

 the attachment, but has none on the outer side, unless we coimt such teeth 

 as in figs. 4 and 8 occur at some distance down the shaft, and cannot be 

 regarded as belonging to the free tip. Probably the long cusp of cescuU 

 represents the outer group of spines that is so short in ilicis, while the 

 group of longer, but still very short, spines forming the inner group in 

 ilicis, are represented in cesculi by the few inner teeth that are so small, 

 or even absent. 



The very minute difi"erence between these two species as regards the 

 structures under consideration, compared with the wide distinction from 

 spini, and still more horn pruni, seems to afford proof that here, as in other 

 characters, the species are most closely related. They also suggest this 

 reflection, that two species believed to be distinct will, if they are so, show 

 some differences in these appendages, minute though they may be, and 

 though they may for long elude detection. 



Explanation of Plate X., Figs. 1 and 2. 



Fig. 1. — iEdeagus of T. cesculi, male. 



Fig. 2. — ^deagus of T. ilicis, male. 

 Only the sedeagus is figured as I find no difference in the other parts of 

 the appendages, and the female appendages, being inconclusive, are also 

 omitted. — J. L. R. 



BUTTEEFLIES OF THE CHILTEENS : WITH A NOTE 

 ON CEETAIN EXOTIC FORMS AT LARGE IN 

 BRITAIN. 



By Hugh Scott, M.A., F.L.S., F.E.S. 



(University Museum of Zoology, Cambridge.) 



The articles in this volume by Mr. Rowland- Brown and the 

 Rev. J. W. Bussey Bell on the butterflies of the Buckinghamshire 

 and Oxfordshire Chilterns have been of great interest to me, since 

 during the past sixteen years I have become closely acquainted 



