The Resin-bees 



choice of this site to which our eye can pene- 

 trate. In the common Snail-shell, whose 

 cavity widens rapidly, the insect establishes it- 

 self much farther back, so that, In order to 

 see the terminal partition, we must, as I have 

 said, make a lateral inlet. The position of 

 this boundary-ceiling, which may come farther 

 forward or farther back, depends on the vari- 

 able diameter of the passage. The cells of 

 the cocoons require a certain length and a 

 certain breadth, which the mother finds by 

 going higher up or lower down in the spiral 

 according to the shape of the shell. When 

 the diameter is suitable, the last whorl is oc- 

 cupied up to the orifice, where the final lid 

 appears, absolutely exposed to view. This is 

 the case with the adult Garden Snail and 

 Helix ccesp'itiim and also with the young Com- 

 mon Snail. We will not linger at present 

 over this peculiarity, the importance of which 

 will become manifest shortly. 



Whether in the front or at the back of the 

 spiral slope, the insect's work ends in a faqade 

 of coarse mosaic, formed of small, angular 

 bits of gravel, firmly cemented with a gum 

 the nature of which has to be ascertained. It 

 is an amber-coloured material, semi-trans- 



309 



