REVIEWS. 83 



general," but contains very little information, merely stating that many 

 of our native species are very beautiful, though^ not rivals to the tropical 

 species, and alluding to the interest excited by the fact no less wonderful, 

 truly, for being known to most -that the transformations of butterflies are 

 but successive rejections of its outward skin by an animal always one and 

 the same in all stages of its existence. 



The general characters of the Imago are treated of in section third, which 

 contains an outline of the principal features of their external anatomy, and 

 the general structure, neuration, and clothing of the wings, with much 

 interesting information about the scales, especially those recently disco- 

 vered to be peculiar to the males of various species of Diurna, belonging 

 to the genera Pieris, Argymnis, Hipparchia, and Polyommatus, and " chiefly 

 found in those species of which the males have the upper surface of the 

 fore wings ornamented with patches of velvet-like hairs." Several figures 

 of these " male scales" are given in the second of the two elementary 

 plates, and are very curious. In the close of the section, Mr. Westwood 

 observes, that the variations in the flight of the different species and 

 tribes have been as yet but slightly investigated. We should be glad to 

 see more attention paid to this subject, as it may not improbably prove of 

 considerable value, and it is difficult to see why a well-defined variation in 

 the modes of flight should not be as important as a difference of structure, 

 on which, indeed, such variations often depend. It may probably be 

 pretty safely affirmed that no two species of our native Diurna have 

 exactly the same kind of flight ; and a careful observation and record of 

 their variations would be at once interesting and instructive, and would, 

 at any rate, save the young collector the trouble of many a laborious 

 chase, ending in fruitless capture. We speak from experience and the 

 memory of past years. 



Section four is devoted to " the preparatory states of Diurnal Lepidop- 

 tera," giving a general sketch of the progress of the insect from the egg to 

 the imago, illustrations of which, from Sepp and Herold, are found in 

 elementary plate B. 



Section six is a description of the two elementary plates, consisting of 

 details of the perfect and preparatory states of butterflies, and forming an 

 important and valuable addition to the work. 



" In this introduction," says Mr. Westwood, " I have embodied the 

 results of a very minute and microscopical examination of a vast number 

 of species, which had been rendered necessary for my completion of the 

 great work on the genera of Diurnal Lepidoptera, commenced by Mr. 

 Edward Doubleday, and in which several important characters, hitherto 



