CHAPTER OF CRITICISM. 149 



him for the figure in Loudon), but I do not think it is by any means proved, 

 since kindred species, such as Pontia rapce ? and P. napi $ have been found 

 in such situation at large, and not " under glasses" (as Mr. B. mentions), also 

 P. cardaminis $ with P. napi $. Mr. Haworth likewise mentions (p. 144), 

 " Spilosoma lubricipeda and menthrasti being united, and suspects urticce to be 

 the produce;" and Mr. Schuckard found an Osmia and Chelostoma, of two 

 different genera, in company, which shows that some caution is necessary in 

 determining species. 



I am, sir, &c, 



James C. Dale. 

 Glanvilles Wootton, April 25, 1837. 



,The Sense of Smell in Carrion Birds. 



To the Editor of the Naturalist. 

 Sir, — My brother's paper on the sense of smell in carrion birds (p. 34) is con- 

 clusive as far as regards that species or genus of which it treats ; but I think 

 there are probably great modifications of the sense in different birds, as we know 

 to be the case in Dogs. I mean that those birds which live on carrion probably 

 have it much keener than those which catch their prey alive, as all the Hawks, 

 Falcons, &c. I think that Hawks fJQuery, the Falconidce ? — Ed.] hold the same 

 place in the feathered race that the Greyhound does among Dogs ; and the Crows, 

 Vultures, &c, correspond to Fox-hounds and Harriers, which hunt by the scent. 



I am, sir, yours, &c, 



Beverley R. Morris. 

 Dublin, April 19, 1837- 



One or two Criticisms. 



To the Editor of the Naturalist. 

 Sir, — In the Magazine of Zoology and Botany, Mr. Duncan supplies a paper 

 which professes to give the characters and descriptions of the Dipterous insects 

 indigenous to Britain, intending, I suppose, to mention all the species. In the 

 genus Oxycera, however, he describes but six species, while in Mr. Curtis's 

 British Entomology for January and February 1833, no less than ten are included. 

 I am aware that one of these, Oxycera affinis, may possibly be only a variety of 

 0. muscaria ; but even supposing that to be the case, there remain three species 

 of which Mr. Duncan takes no notice. Now Mr. Duncan either had seen 

 Curtis's splendid work, or he had not. If he had, I am at a loss to find any 

 excuse for such an omission ; if he had not, he ought never to have attempted 



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