The Ammophilae 



tude, landmarks, in short, all the minutlje of 

 geometry. 



The temporary closing of the burrow with 

 a flat stone, as practised by the Sandy Ammo- 

 phila and the Silvery Animophila, is ap- 

 parently unknown to the other two spe- 

 cies. At any rate, I never saw their homes 

 protected by a lid. Besides, this absence 

 of a provisional door seems to be obliga- 

 tory upon the Hairy Ammophila. 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 pass- 

 ing, so perhaps the Silky Ammophila neg- 

 lects the precaution of placing a stone over 

 a well down which she has to go at least five 

 times in a short space of time. 



In the case of all four, the provisions of 

 259 



