86 DISCREPANCIES. 



Cape de Yerd Islands, and twelve hundred from Guada- 

 loupe, he observed a large butterfly, apparently of the 

 genus Morpho, (?)* flying round the ship, but he could not 

 succeed in capturing it. These are facts related by entomo- 

 logists who could not have mistaken the objects observed, 

 and consequently they are entitled to full credit. They 

 are full of interest in relation to a subject of physiological 

 discussion, the power of flight supposed to be possessed 

 by these, our little favourites, and the sj^eed with which 

 they are conveyed across the ocean, whether by an actual 

 expenditure of muscular energy, or whether carried by the 

 force of the wind alone. My own opinion certainly is, 

 that the amount of muscular power exerted during flight 

 is trifling, compared with what we have usually supposed 

 it to be, and that in these instances the insects have been 

 greatly aided in their progress by the wind. The speed 

 at which they must have traversed the ocean seems to 

 confirm this view ; as it is well known that the JEslma 

 will not live more than a few days, if unable to obtain its 

 living food.'' 



The Atlantic being the great highway of nations, we 

 have more abundant observations on this than on other 

 oceans, but similar phenomena exist elsewhere. Hum- 

 boldt mentions having seen, in the Pacific, at a vast dis- 



* If the butterfly was indeed a Morpho, — and Mr Dyson, who was an 

 experienced lepidopterist, could scarcely have been deceived about so 

 remarkable a butterfly, — it could have come neither from the Cape de 

 Verd Isles nor the Antilles, but from the continent of South America, 

 to which the genus Morpho is limited. The nearest part of that con- 

 tinent is not less than one thousand five hundi-ed miles from the posi- 

 tion of the observer. 



