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parallel. Three other species are found in North America — the 

 Mango Humming Bird, which was procured by Mr. Audubon on 

 the Florida Keys ; the two others, T. anna and S. rufus, have 

 been observed only on the western side of the continent — while in 

 the tropical climates, a large number of species are known to 

 exist. 



Various speculations have been offered relative to the production 

 of the brilliant and varied hues peculiar to the male — and being 

 unable to explain why it should possess such brilliant metallic lus- 

 tre, I cannot do better than give the following remarks on Hum- 

 ming Birds, by Sir William Jardine, Bart., contained in the Natu- 

 ralist's Library, vol. 1, page 83. 



" The structure of the feathers, which shine with so much lustre, 

 has occupied the attention of most of their describers. Audibert 

 has tried to demonstrate the cause on mathematical principles, the 

 form of the feathers, and the manner in which the light strikes 

 them; while Lesson is of opinion that the colors are due to ele- 

 ments contained in the blood, and diffused by circulation. He says, 

 at the same time, that all the barbules and plumelets are deeply 

 furrowed in the centre, and the light, when striking vertically, 

 produces no color, or only black ; but when striking transversely, 

 every opposite side of the furrow acts as a reflector to the others, 

 and in this way assists in producing the colors." 



Bullock, when speaking of the same subject, says that " The 

 preserved specimens u r ere but the shadow in brilliancy to what 

 they were in life." 



The only opportunity which I have had of comparing preserved 

 specimens with the living, is with the present species, and in all my 

 comparisons, I observed but little or no difference. From this it 

 would seem that the circulation had but little to do with it, and that 

 we must trace it to some other cause than elements contained in 

 the blood. These theories, however, are fanciful, and for want of 

 a better, I am willing to adopt that part of Lesson's remarks 

 which appears to me the most plausible — that it is attributable to 

 the formation of the feathers, and the manner in which the light 

 strikes them. 



