Insects. 



6065 



racic feet and a spot on each of the prolegs black. After this they 

 did not appear to alter much in the succeeding moults, and I was pre- 

 vented from completing my observations upon these interesting larvae 

 by the demise of the last one, before it was full grown ; but some of 

 the English entomologists were more successful, and, I believe, 

 obtained the pupae. R. F. Logan. 



Geographical Distribution of British Butterflies. — The paper on this subject by- 

 Messrs. Boyd and More, at p. 6018 of the 'Zoologist,' is one of those careful and 

 thoughtful papers which give rae the greatest pleasure to receive and publish : it has, 

 however, suggested a few doubts in my mind, the solution of which will, I am sure, 

 be as interesting to my readers as to myself. In the first place, I feel a strong 

 repugnance to adopting any theory of geographical distribution of insects that does 

 not recognise as a primary postulate the abundant presence of suitable food, and, 

 as a secondary postulate, suitable conditions of climate, whether as regards heat or 

 moisture: thus, as a familiar illustration, I suppose that Brassicae and Rapse swarm 

 in our London gardens, first, because we provide them so abundantly with suitable 

 food, and, secondly, because they find the temperature of the London atmosphere 

 conducive to their well being and increase. I cannot imagine that the clouds of 

 white butterflies I sometimes see opposite my window are the descendants of a colony 

 settled there some hundreds of thousands of years ago, but that they are attracted 

 simply by the rows of cabbages, and I arrive at this conclusion because when the field 

 is occupied by a crop that the white butterflies do not seek, I do not see them there. 

 Again, for several years we had lucerne near us, and the field produced an abundant 

 crop of Polyommatus Alexis, but now mangold wurzel has succeeded the lucerne, and 

 Alexis has deserted us : surely in our theories we should allow margin for such 

 obvious causes of the presence or absence of species. I may also observe that any 

 conclusions drawn from data so obviously imperfect as those to which Messrs. Boyd 

 and More have had access, while they aim at rigid truth, may convey a totally false 

 impression. Thus I think that working entomologists would agree with me that the 

 gloriously varied "Province" of *' South Wales" was likely to prove the richest in 

 butterflies of all the eighteen, and " Ouse," on account of its monotonous surface, to 

 prove the poorest, but we find that the butterflies of " South Wales" stand at 0, those 

 of Ouse at 59. In both instances the facts of the case are misstated, simply because 

 the absence or presence of butterflies is inferred from the absence or presence of 

 entomologists. — Edward Newman. 



Additions to Messrs. Boyd and More's " Geographical Distribution of Butterflies in 

 Great Britain." — 



Anthocaris Cardamines. Area 15. Very plentiful at Fochabers. 



Vanessa Antiopa. Area 13. Two specimens taken several years ago on the 

 banks of the canal, not far from Paisley ; one of these, a few years ago, was in the 

 possession of a bird-stuff'er in George's Street, Edinburgh. 



Salyrus Tithonus. Area 11. Taken by myself at Morpeth: T believe it is also 

 plentiful in the neighbourhood of Durham. 



Area 6. This is without a single representative. Has no one visited this portion 

 of South Wales who is able to supply any information ?—John Scott ; Southfield 

 Villas, Middlesbro'on-Tees, April 5, 1858. 



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