THE YOUNG NATURALIST. 



61 



largest flight the species is rarely seen the next year. The common name of 

 this species, the Camberwell Butterfly, also points to a time when it was 

 commoner than now, and had at least one recognised locality. 



III. Immigrants that breed here but seem unable to 



PERPETUATE THEIR RACE (&). 



These are the two Clouded Yellows, Colias Hyale and Edusa. The 

 former of these {Hyale) appears at very uncertain intervals. Sometimes 

 like Daplidice and Lathonia it crosses singly, at others a swarm of greater or 

 less magnitude reaches us. When a large flight arrives in the early part of 

 the season they will breed here, and the second brood appears in due 

 time. But few are able to survive the winter, and after the largest flights 

 the species seldom appears the next spring. Edusa is evidently hardier than its 

 near relative, and sometimes lingers on for several generations in our southern 

 counties. In the last great "Edusa year" it certainly bred in some numbers 

 in this county (Durham), one of the most northern and exposed of all. But 

 it seems unable to maintain its footing in the Island, and but for immigra- 

 tion it would soon be numbered with the extinct species. 



IV. Species that are rapidly disappearing (3). 



1. LycjENa Acis has long been among our rarest natives. Many localities 

 are named by older writers where it no longer occurs. I do not personally 

 know of any place where it can now be taken. The last I knew of was at 

 Penarth, near Cardiff, but the fields where it was taken are now built on. 

 Possibly there may be some similar places in the neighbourhood where it 

 might still be found, but if not extinct it soon will be. 



2. Ly&ena Arion. After the full account of the disappearance of this 

 butterfly, in the EMM. for last year, it is unnecessary for me to enlarge 

 upon it here. It may, of course, re-establish itself in its old localities or 

 some of them, if we had a few favourable seasons, but it is evidently doomed 

 to early extinction. 



3. Thecla Prom. I place this species under this head with some hesi- 

 tation, for I really know very little about it. It was only added to our list 

 within the time of the present generation of Entomologists, and it has never 

 been either common or widely distributed. 



Y. Species whose range is becoming restricted (11). 



Under this head I am obliged to place several common species, and as the 

 list is long, I will make my remarks on each as brief as possible. 



1. Papilio Machaon. Eormerly extending northward to Beverley at 

 least, (see Porritt's " List of Yorkshire Lepidopt era "), and once a common 



