3<d The Field Naturalist's Quarterly Feb. 



did not find a single case of this spider having fallen a prey 

 to one Pompilid. 



And now let me return for a moment to the great anxiety 

 betrayed by the insect with regard to the front-door of her 

 burrow. The sand is very loose, and when dry is constantly 

 slipping down in petty avalanches, and thus must^ frequently 

 smother up the hole already made, and then cause very real 

 inconvenience and trouble to this Fossor ; hence it is very 

 natural and excusable that she should constantly feel it 

 incumbent upon her to satisfy her mind that no such 

 disaster has befallen her domicile. And here I may 

 mention that I hardly ever saw one of these Pompilids 

 succeed in making a fresh hole for itself by working inwards 

 from the surface : in fact, I believe they are unable to do so 

 unless the surface sand is just moist with dew or light rain, 

 and will hold together instead of falling in as fast as a hole 

 is made. It is a much easier matter to make a burrow by 

 working from within outwards, as my accidentally im- 

 prisoned specimen had to do ; for then, at any rate, the 

 driest, loosest sand will not be encountered till all the rest 

 of the burrow is complete, and, moreover, the body of the 

 operator helps to keep an open passage-way and to press the 

 sides of the burrow firmly so as to give them more strength. 

 I never saw specimens of P. plumbeus out after 5 p.m. in 

 August ; they had all retired into their burrows for the 

 night, and from these they usually emerged between 10 

 and it o'clock next morning, before the sun had completely 

 dried the surface sand, and it is well to remember that the 

 larval and pupal stages are passed beneath the surface in 

 the midst of decomposing spiders, and that one of the first 

 acts of the young imago is to dig her way out to the surface 

 from the depths below. 



A somewhat curious point about those sun-loving insects 

 is their inability to withstand a comparatively slight rise 

 of temperature. I have seen P. plumbeus in full vigour one 

 moment and fall dead the next as it ran on to a patch of 

 very hot sand, so hot that I could only just bear it with my 

 hand. Other insects, too, are similarly affected : at the 

 foot of every little bare patch of sand facing south, or within 

 a point or two of south, were to be seen heaps of dead 



