76 MODERN CLASSIFICATION OF INSECTS. 



for about an inch around it effervesced much in the same way as a 

 Seidlitz powder. The typical species Brachinus crepitans Linn.., is 

 not uncommon, being found in company under stones ; and it is 

 stated that these communities have been found at times to consist of 

 at least a thousand individuals. The effect of this vapour upon the 

 skin is very similar to that produced by nitric acid. M. Dufour has 

 published a description of the organs by which this fluid is secreted in 

 the Brachinus balista, which will be found in the eighteenth volume of 

 the Annates clu Museum, as well as in the sixth volume of the An- 

 nales des Sciences Naturelles.* Kuhn has also published an account 

 of the habits of these insects in the thirteenth volume of Der Natur- 

 forscher. Some authors have thrown doubts upon the statement that 

 the explosion of these insects is accompanied by a noise ; the fol- 

 lowing circumstance, however, communicated to me by the celebrated 

 traveller Burchell, will be sufficient (were other evidence wanting, 

 which is not the case) to confirm the correctness of the recorded 

 statements. Whilst resting for the night on the banks of one of the 

 large South American rivers, he went out with a lantern to make an 

 astronomical observation, accompanied by one of his black servant 

 boys ; and as they were proceeding, their attention was directed to 

 numerous beetles running about upon the shore, which, when cap- 

 tured, proved to be specimens of a large species of Brachinus: on 

 being seized they immediately began to play off their artillery, burning 

 and staining the flesh to such a degree, that only a few specimens 

 could be captured with the naked hand, leaving a mark which re- 

 mained for a considerable time ; upon observing the whitish vapour 

 by which the explosions were accompanied, the negro exclaimed 

 in his broken English, with evident surprise, "Ah I massa, they 

 make smoke." The late traveller, Ritchie, communicated to Mr. 

 MacLeay some particulars respecting this secretion ; his companion, 

 M. Dupont, having taken a nest consisting of more than a thousand 

 individuals near Tripoli. He says the crepitating matter made 

 Dupont's fingers entirely black when he took them : it is neither al- 

 kaline nor acid, and it is soluble in water and in alcohol {Kirhy and 

 Sjience, Int. iv. p. l^S.). From a communication made by Mr. Holme 

 to the Entomological Society {Trans. \o\. W. p. 7.), it would appear 

 that the crepitation may be produced for a considerable time after the 



* Also in the " Recherches Anatomiques," p. 204, 



