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an inch wide and four or five inches long. The earth is removed from these 

 and fornn the little heaps on the surface already alluded to. Each of these 

 horizontal tunnels contains one egg and a store of pubiUum. The rounded 

 further end is firmly and tightly packed \vith concentric layers of the material 

 brought down, and in the centre of these layers is a beautifully constructed 

 cavity containing the egg. This cavity is about half an inch deep by gths high ; 

 it is oven shaped, having a slightly hollow floor and a highly arched roof, the 

 front or last finished side being nearly perpendicular. This cavity is carefully 

 lined with, perhaps I ought to say formed of, a thin layer of earth worked to 

 ;i clay like consistence, nicely smoothed and finished, and often marked by the 

 front tiliial of the beetles, as if they had used them as trowels. The total 

 capacity of the cavity would be sufficient to hold half a dozen eggs, one only, 

 however lies loose on the floor ; it is beautifully clean and white, quite unsoiled 

 by the clay surrounding it, nor is a loose particle of any kind often to be found 

 in the cavity. How the beetles manage to close it without allowing earth to 

 fall in it is difficult to imagine, and I dj not know how the process could be 

 observed. The material immediately following is placed rather loosely, but 

 the rest of the tunnel is tightly crammed, layer upon layer, similarly to the 

 first portions. The last half or three-tiuarters of an inch next the perpendicu- 

 lar burrow is closed in with earth — no doubt a portion of that removed from a 

 new tunnel begun on the completion of the first. 



The egg is 3-Gths of an inch in length, rather thicker (1-lOth of an inch) 

 at one end than the other, and slightly c mtracted in the middle ; it is of a 

 pale, straw colom-, very delicate and easOy broken. Before the yoving larva 

 is hatched the egg inci-eases slightly in length and becomes of nearly double 

 the previous diameter — viz., Jth. This appears to arise from imbibition of fluid 

 and possibly also of air. The young larva devours the stored pabulum, pass- 

 ing along the centre of the tunnel to the opposite end, and then returns. I 

 believe it makes two such complete journeys before it is full, which it is in the 

 following July, when it constructs a cocoon or cavity of firmly jiressed earth 

 at the same end of the tunnel as the egg originally oocuiiied. Here it assumes 

 the proper state and deoomes perfect in the following August or September. 



These arrangements so carefully made by Geotrapes stercorarius are 

 turned to account by Aphodius porcus. At or about the time Geotrupes 

 stercorarius is constracting the egg cavity, the female of Aphodius porcus 

 arrives and makes her way into it. Here she lays her own eggs — these 

 are spherical, of rather less than 1"20 in diameter. She arranges them in the 

 surrounding material each in a separate little spherical cavity as carefully 

 constructed as that of Geotrupes stercorarius, and in affording these little 

 spaces, the larger space of Stercorarius' egg cavity is used up ; but, at the 

 same time, the egg of Stercorarius disappears, and then the Aphodius porcus 

 succeeds in (juitting the tunnel. I do not know how long this jjrocess takes, 

 but I believe about a week. I have counted as many as ten eggs of Porcus so 

 arranged, and I believe I have seen more when I had not counted them. 



