452 On the Mus ortliodon of Ile/iseJ. 



characteristics — tliat is to say, the development of the red 

 species of Catocala — would be simply impossible, firstly in a 

 region in which a series of foes exists capable of noiselessly 

 approaching the moth as it rests upon the tree-trunk, and 

 secondly where, on being pursued, owing to limited space 

 and in consequence of the absence of a definite perspective, 

 the insect cannot terminate its distracting flight and turn its 

 distracting colour to account. To these circumstances is to 

 be ascribed the fact that the red Catocala is widely distributed 

 in the Nearctic and Paltearctic Regions, but does not occur 

 in the Tropics. And it appears to be further deserving of 

 note that in the Neotropical and Australian Regions, which 

 have an older character, nothing is known of any represen- 

 tatives of the genus Catocala at all. 



A glance at the recent species of Catocala will serve to 

 confirm the interpretation here given ; almost all the red 

 species of Catocala are moths of a size which the yellow 

 species of Catocala in most cases fall far short of. The 

 marking of the red species of Catocala, consisting of two 

 black transverse bands, is, almost without exception, absolutely 

 regular in its occurrence, while the yellow species show 

 manifold modifications. Another interesting fact is that the 



e size 



orange-coloured species of Catocala are also of lar^ 

 while their marking, which consists of two black transverse 

 bands, remains more or less constant ; in the case of the 

 yellow species, on the other hand, it is generally only among 

 the larger representatives that we find the marking in question 

 regular in its development. At the same time, however, it is 

 self-evident that local and historical conditions must have 

 produced a series of modifications both in size as also in 

 coloration in the case of the red species of Catocala as well ; 

 in them nevertheless these modifications are, as has already 

 been mentioned, much less considerable. As a characteristic 

 representative of the coloration that we have been investi- 

 gating, Catocala elocata, Esp., may be taken. This species is 

 one of the largest of the genus Catocala, and at the same 

 time one of the commonest of European moths. 



LII. — On the Mus orthodon of Hens el. 



To the Editors of the ^Annals and Magazine of 

 Natural History.'' 



Gentlemen, — In 1900, while preparing a paper for the 

 P. Z. S. (pp. 387-428) on Mus sylvaticus and its allies, I 

 had occasion to examine and discuss the Mus orthodon of 



