Stridaluling-organ in an Egyptian Beetle. lo7 



It was more easily heard than seen, on account of the tolerably- 

 distinct stridulation, resembling the word xexe contitmally 

 repeated, which it produced by rubbing the inner side of the 

 lemur of the posterior legs asfainst the edges of the elytra 

 which border the abdomen. When several were shut in a 

 bottle, they speedily tore each other to pieces with a fury 

 greater than that of all other Carabidte. 



Tiiis account contains many observations of interest. In 

 the first place, the author, although apparently unacquainted 

 with the structure of the stridulator, noticed tliat the sound 

 proceeded from friction between the posterior femora and the 

 elytra. In the second place, the statements as to the abund- 

 ance, ferocity, and fearlessness of the beetle in roaming 

 abroad in midday and adverti:;ing itself by stridulation point 

 to the conclusion that the species is protected and that the 

 stridulation has the same function as that commonly assigned 

 to similar sounds emitted by scorpions, " Mygales," rattle- 

 snakes, and other poisonous or nauseous animals. This 

 opinion is strengthened by the equal development of the 

 organ in the two sexes, which precludes the likelihood of its 

 ])rimary use as a sexual stridulator helping the male to find 

 the female or vice versa. Anyone accustomed t^ handling 

 Carabidffi, and familiar with the extreme offensiveness of the 

 odour so many of them give out under provocation, will 

 leadily appreciate the cogency of the argument in favour of 

 the distastefulness of Graphipterus, seeing how intimately 

 f'orniected in ourselves are the sensations of taste and smell. 

 The shining black or metallic hue so characteristic of the 

 Carabidai and rendering them such conspicuous objects is 

 perhaps correlated with this offensiveness, and acts as its 

 advertiser. 



On the other hand, there can be no doubt, I think, that 

 Graphipterus is protectively coloured, the black and white 

 speckling of its dorsal surface being admirably suited to 

 harmonize with the mottled tint of the sand in which it lives; 

 and the expanded and somewhat flattened shape of the abdo- 

 men suggests tliat when the necessity for concealment for 

 capture of prey or escape from enemies superven 'S, tlie beetle 

 sniks into the sand, leaving only the upperside of its body 

 exposed on the surface. 



The combination of procryptic coloration with aposematic 

 characters is by no means uncommon in the animal kingdom. 

 The cobra furnishes an instance amongst snakes *, and the 

 Indian Mygsde known as /VeciVo^^eria amongst spiders. Tiie 



* "Wallace, ' D.irwinisni,' p. LH)i'. 

 Ann cC- May. N. Hist. Ser. 7. Vol. x. 1,2 



