26 Mr Goodman, On a striking instance of Mimicry, [Feb. 12, 



the nape russet brown. The whole thorax is russet brown (a 

 yellow dot on the scale of the front wing being sometimes an 

 exception to this). 



Considering the abdomen of the female and worker to consist 

 of six segments and that of the male of seven, the first segment is 

 of the same russet brown colour as the thorax, but has a narrow 

 (in some specimens a very narrow) border of yellow at the hind 

 mai'gin. The second segment is wholly russet brown. The third 

 and fourth are bright yellow, with the exception of a spot or dash 

 of russet brown on each side of each segment, with sometimes an 

 indication of a dorsal line running through the light zone and 

 ending in the front part of the third segment and the hind part of 

 the fourth segment in a wedge-shaped mark. The fifth, sixth, 

 (and in the male) seventh segments are russet brown. 



The wings are rufous brown at the cortal margin, shading into 

 dull brown at the inner margin. The legs are long, strong, and 

 rufous throughout. 



Corresponding to the colouring of this species the Laphria is of 

 almost precisely the same russet brown colour, with the exception 

 of the face and the fourth and fifth segments of the abdomen, 

 which are bright yellow ; while on each side of each of these seg- 

 ments is a dot of brown. These dots are minute but quite distinct, 

 and sometimes there is an indication of a dorsal line. The wings 

 are of russet brown somewhat richer than the hornet, while the 

 hind and inner margins are washed with a duller brown. The 

 limbs are stout and large, brown, and clothed with reddish hairs. 



The only want of correspondence is in the hind margin of the 

 first segment of the abdomen, in which the narrow band of yellow 

 in the hornet has nothing corresponding to it in the fly. 



I need hardly remark that the structures which underlie this 

 apparent correspondence are wholly dissimilar, there being no 

 closer homology between the hymenopterous and dipterous insect 

 than between a zebra and a tiger. More than this, it is singular 

 to find that the same visual effect is caused by wholly different 

 circumstances ; for, while it is the surface of the comparatively 

 smooth armour of the hornet which is itself coloured russet brown 

 and bright yellow; the colour of the Laphria is caused by a dense 

 pile of ochreous hairs almost hiding the nearly black chitonic 

 integument, and the yellow is wholly reflected from the hairs 

 themselves. 



Although the flight of the Laphria is, as one would suppose 

 from the less proportional size of its wings, less sustained than 

 that of the Vespa, while it lasts it is very much like it, and 

 is accompanied by a buzzing sound, especially in starting and 

 alighting. 



The abdomen of the Yespa is conical and boldly arched in 



