Birds. 6879 



its long forked tail and more rapid flight, but might easily be taken 

 for the English bird, H. rustica, but it is, 1 think, ruddier beneath, 

 and has on the outer vane of each tail-feather a conspicuous uhite 

 oval spot. It may possibly prove to be the American barn swallow 

 {H. horreorum ; H. americanay Wils.), as I learn from a very care- 

 ful paper, published by Messrs. Newton, in the ' Ibis,' on the birds of 

 St. Croix, that they visit that island during the autumn, but in the 

 same transient way, * 



" P.S. — The scenery has taken up a larger portion of my letter 

 than I contemplated, but I was desirous of carrying into effect your 

 valued recommendation of more description of this. I also thought 

 it might aid to give a notion of the causes which combine greatly to 

 influence the Ornithology of this district. I can scarcely hope I 

 have succeeded ; but I thought my only chance was, not to attempt 

 to convey impressions merely, but to endeavour to pourtray a few of 

 the more salient and peculiar features. The geology seemed the best 

 means of doing this, but I have kept to points which I could examine 

 for myself, and which appeared quite undeniable. In this I have 

 been greatly assisted by De la Beche's map. 



" Errata. — May I be permitted to make the following coiTections of 

 statements in my last letter on Chordeiles : — 



" 1. Since writing it an opportunity has been afibrded me of re 

 perusing White's ' Natural History of Selborne.' I cannot find the 

 remarks I quoted ; I have therefore erroneously given him as the 

 author of observations I have seen elsewhere. 



" 2. I have said, * But if the insect intercept the ray, then its 

 vibrating gauzy wings enable us to see it at a considerable distance.* 

 This is wrong, because, if it intercepted the light, it would appear 

 black. What I should have said is, * But, seen against the shadow 

 of objects, whilst the insect itself reflects a strong light, its vibrating 

 gauzy wings enable us to see it at a considerable distance.' 



" 3. A subsequent sentence should stand thus : — 'May we suppose 

 the eye of the swallow has the same power under whatever circum- 

 stances the ray is reflected ? ' 



"I am greatly tasking your friendly interest in thus sending a let- 

 ter of errata, but I feel assured you will understand my desire to have 

 my statements as correct as possible. 



" I have, during the past week, been exploring the lagoons and 

 artificial canals of this low-lying district, but not with any great 



* Or H. fulva, VieilL, perhaps ; but neither of these species has any white on the 

 vanes of the tail-feathers. — P. H. G. 



