44 CHARLES DARWIN 



quently alights on the trunks of trees. On these occasions 

 its head is invariably placed downwards ; and its wings are 

 expanded in a horizontal plane, instead of being folded verti- 

 cally, as is commonly the case. This is the only butterfly 

 which I have ever seen, that uses its legs for running. Not 

 being aware of this fact, the insect, more than once, as I 

 cautiously approached with my forceps, shuffled on one side 

 just as the instrument was on the point of closing, and thus 

 escaped. But a far more singular fact is the power which 

 this species possesses of making a noise. 8 Several times when 

 a pair, probably male and female, were chasing each other 

 in an irregular course, they passed within a few yards of me ; 

 and I distinctly heard a clicking noise, similar to that pro- 

 duced by a toothed wheel passing under a spring catch. The 

 noise was continued at short intervals, and could be dis- 

 tinguished at about twenty yards' distance: I am certain 

 there is no error in the observation. 



I was disappointed in the general aspect of the Coleop- 

 tera. The number of minute and obscurely coloured beetles 

 is exceedingly great. 7 The cabinets of Europe can, as yet, 

 boast only of the larger species from tropical climates. It 

 is sufficient to disturb the composure of an entomologist's 

 mind, to look forward to the future dimensions of a com- 

 plete catalogue. The carnivorous beetles, or Carabidae, ap- 

 pear in extremely few numbers within the tropics: this is 

 the more remarkable when compared to the case of the car- 

 nivorous quadrupeds, which are so abundant in hot coun- 

 tries. I was struck with this observation both on entering 

 Brazil, and when I saw the many elegant and active forms 

 of the Harpalidse re-appearing on the temperate plains of 



Mr. Doubleday has lately described (before the Entomological Society, 

 March 3rd, 1845) a peculiar structure in the wings of this butterfly, which 

 seems to be the means of its making its noise. He says, " It is remarkable 

 for having a sort of drum at the base of the fore wings, between the costal 

 nervure and the subcostal. These two nervures, moreover, have a peculiar 

 screw-like diaphragm or vessel in the interior." I find in LangsdorfFs 

 travels (in the years 1803-7, P- 74) it is said, that in the island of St. 

 Catherine's on the coast of Brazil, a butterfly called Februa Hoffmanseggi, 

 makes a noise, when flying away, like a rattle. 



7 1 may mention, as a common instance of one day's (June 23rd) col- 

 lecting, when I was not attending particularly to the Coleoptera, that I 

 caught sixty-eight species of that order. Among these, there were only 

 two of the Carabidae, four Brachelytra, fifteen Rhyncpphora, and fourteen 

 of the Chrysomelidae. Thirty-seven species of Arachnidae, which I brought 

 home, will be sufficient to prove that I was not paying overmuch attention 

 to the generally favoured order of Coleoptera. 



