1869.1 



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forcing her way through the earthon wall just after it ia closed in. There she eats 

 the egg of stercomrius, a mass as large as herself, greater, I suspect, if reckoned 

 by weight. My observations do not show how long this takes her, but I should, 

 judging from the different stages at which I have seen the operation, consider a 

 week as about the time employed. When this is completed, she succeeds in quitting 

 the tunnel. The eggs of A. porcus are laid, each by itself in a little spherical 

 cavity, as carefully formed as that of stercorariuSy though not lined with earth, but 

 similarly much larger than the egg itself, which is almost a sphere of a little under 

 inch [in diameter. These little cavities are irregularly disposed in the pabu- 

 lum surrounding the cavity made by stercorarms, the space of which is, finally, 

 almost entirely used up in affording tne spaces around porcus^ eggs. I have 

 counted as many as ten porcus* eggs so disposed, and believe there were frequently 

 more, in instances in which I did not count them. In the mean time, the egg of 

 stercomrius becomes flaccid and finally disappears j and I have several times seen 

 A. porcus' nose applied to it, as if discussing its contents. 



As to the extent to which A. porcus destroys the eggs of stercomrius, I have a 

 note, dated Sept. 21st, 1868, that I brought home the contents of 29 tunnels, on ex- 

 amining which, 15 appeared undisturbed, 6 contained porcus at work, and 8 had 

 been visited and quitted by porcus. In these, the only cavities present were those 

 around porcus^ eggs. No trace of stercorarius' eggs remained, and only the dis- 

 turbed clay represented its surrounding cavity, 4. _pomts having completed her work 

 and disappeared. 



On another occasion (Oct. 6th), I took 13 A. porcus in the tunnels of 0. ster- 

 corarius, under one patch of cow dropping. In this instance, only a fourth of 

 stercorarius eggs were undisturbed by A. porcus. On two occasions, I have found 

 three A. porcus in one egg cavity, and several times two. I did not ascertain 

 whether these were <J and 9 > but suppose them to be females accidentally met on the 

 same errand. 



I have never taken A. porciis elsewhere than in the egg cavity of G. stercorarius' 

 nest, except on one occasion, when, for the purpose of making this comparison, I 

 instituted a careful search for it in the loose dung lying on the surface. In about 

 an hour I found four. I then devoted an equal time to a search in their favourite 

 habitat beside stercorarius' egg, and found twelve. Though several common 

 Aphodii and other beetles swarmed in the droppings beneath v^hich stercora.rius was 

 at work, I never found any other beetle in his burrows, except an occasional elytron, 

 as though only the remains, after some predaceous beetle had devoured it, had been 

 accidentally brought down with the stores of pabulum. I once found the remains 

 of a beetle squeezed flat against the end of a burrow, obviously by the tight-packing 

 process of G. stercorarius. This, on examination, proved to have been an A.porcus^ 

 which had probably gone down a little too soon. In undisturbed tunnels, no traces 

 of such eggs as those of porcus could be found, though a smaU larva {Aphodiam, ? ) 

 occasionally occurred somewhere in the length of the burrow, the egg having 

 probably been accidentally brought down. These observations prove that A. porcus 

 destroys the egg of G. stercorarius, replacing it by her ovm. Some doubt may 

 exist as to her eating it, as it is possible that it is injured by hertibiee, &c., and that 

 its contents soak into the sm'rounding matei'ial. Still, were this so, the egg would 

 surely sometimes escape : its disappearance would not exist paripassii with porcus* 



