The Ammophilce 239 



on the spot to which chance has taken her. 

 The vagabond's guide is her topographical 

 memory, whose marvellous feats I shall have 

 to tell later. As for me, in order to return next 

 day to the well hidden under the lid of the little 

 flat stone, I dared not trust to my unaided 

 memory : I needed notes, sketches, lines of 

 latitude and longitude, landmarks — in short, 

 all the minutiae of geometry. 



The temporary closing of the burrow with a 

 flat stone, as practised by the Sandy Ammo- 

 phila and the Silvery Ammophila, is apparently 

 unknown to the other two species. At any 

 rate, I never saw their homes protected by a lid. 

 Besides, this absence of a provisional door 

 seems to be obligatory upon the Hairy Ammo- 

 phila. In fact, as far as I could see, this species 

 hunts its prey first and then digs its burrow near 

 the place of capture. In this way the storing 

 of the provisions can be done straight away ; 

 and there is no need to trouble about a lid. As 

 for the Silky Ammophila, I suspect that she has 

 another reason for not employing a temporary 

 cover. Whereas the three others put only one 

 caterpillar in each burrow, she puts in as many 

 as five, though much smaller ones. Just as we 

 ourselves neglect to shut a door through which 

 we are constantly passing, so perhaps the Silky 

 Ammophila neglects the precaution of placing a 



