206 TXDEX. 



Tropics, exuberance of the, 27, 28 ; relative proportions of the insect 



tribes within the, 28, 29. 

 Tychius, always apterous in Madeira, 82. 



Unity, indicated in the organic creation, 179, 180. 



Vanessa Atalanta, Linn., has a different aspect in N. America, 34 ; 



perhaps a recent introduction into Madeira, 74. 

 Callirhoe, Fabr., smaller in Porto Santo than in Madeira, 73. 

 Variation in the Insecta, a matter of experience, 7? 8, 15 ; probable 



from analogy, 15; perhaps indicated in every individual, 16, 17, 



18 ; restricted, 35. 

 Variety, definition of the term, 4. 

 Velia, on the development of the wings of, 100. 



Waterhouse, Mr., his opinion concerning generic types, 172. 



Westwood, Mr., on Papilio Machaon from the Himalayas, 32 ; on 

 American specimens of Lyccena Phloeas, 34 ; on the effect of heat 

 in developing the wings of insects, 44 ; on a winged state of 

 Choreius ineptus, 44 ; on the development of the wings in Del- 

 phax, 45 ; on a winged state of Cimex lectularius, 45 ; on Aphelo- 

 cheirus cestivalis, 100; on the development of the wings of the 

 Hydrometridee, 100; on Cimex apterus, 100; on Prostemma gut- 

 tula and Coranus subapterus, 101 ; on the development of the 

 wings of Lygceus brevipennis, 101. 



Whewell, Dr., on the natural causes which science has to investi- 

 gate, 191. 



White-Cabbage Butterfly, varies in Nepaul and Japan, 34. 



Winds, the effects of, in the diffusion of insects, 148. 



Wings of insects, subject to undue development in hot seasons, 43 ; 

 liable to become gradually obsolete in islands, 81 ; more variable 

 than other organs, 97. 



Xenostrongylus, its geographical distribution, 124 ; common to 

 Madeira and Sicily, 139. 



Zargus pellucidus, Woll., variety of, on one of the Madeira Islands, 



88. 



FINIS. 



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