( ei ) 



We have ailo])teil this kiuil of coniR't.'.tioii f'oi' the sake of simplicity of printing. 

 Tlie pedigree should road as follows : — 



Rhodosoma Cizara Rethera Bnjiimini/d 



If connected like this, each genus may have acquired its own specialisations after 

 tlie jioiut of separation, and each may also have preserved aeneralisations lost 

 by the nearest allies after separation. 



GEOGRAPHICAL DISTBIBUTION'. 



The Hawk Moths are an essentially tropical family, the nnniber of 

 species existing in the temperate regions being comparatively small. Very 

 few ^jAi//ffi(/ai- extend into the Arctic Regions, and then only as occasional 

 visitors, no species being known to breed beyond the Arctic Circle, though some 

 {Amorpha popidi and anmrensis, Sphinx ocellati, Celerio (/all//, Ili/loictis 

 piiiasti-i) may be expected to occur as far north as their food-plants go. As 

 the greater number of species have a powerful flight, and are, moreover, often 

 wanderers, covering wide distances, the area inhabited by some of the species 

 is very extensive. 



The proportion of geographically uniform species of Sphuiyidae is large as 

 compared with other families of Lepidoptera. Methodical research has proved 

 to the systematist that countries like West and East Africa, India and the 

 Malayan Islands, Central and Soutii America and the Antilles, the Andes and 

 Eastern Brazil, etc., etc., are inhabited by special races of nearly every species 

 of Butterfly there occurring. The student is, a prioi-i, certain in most cases 

 that a species of Butterfly not yet discovered in some such district will, if 

 occurring, exhibit some kind of distinction. In Sphingidae a p/-iori conclusions 

 like this would mostly be wrong. Since geographical variation depends on 

 geographical isolation, it is evident that those Lepidoptera which are stationary 

 are far more variable geographically than those which are not prevented by 

 geographical barriers from constantly crossing over to other districts. The 

 power of flight, however, is as such no factor eflacing the geographical 

 barriers. The swil't-flying Charaxes and Papil/o vary geographically as much 

 as do slow-flying Butterflies ; and in birds — which may be called stationary 

 from the point of viesv of a student of geographical distribution in so far as 

 they hreed in their native country — geographical variation is also the rule and 

 not the exception. On the contrary, the more powerful the flight, the more is 

 all animal enabled to flee from or resist the factors of passive distribution 

 (water and wind;, to counteract their influence. But if powerful flight and the 

 lialiit of wandering during the period of [iropagation coincide in a species, the 



