Bramble-bees and Others 



males and now by two females. The most fre- 

 quent arrangement was the simultaneous 

 presence of both sexes, with the female in 

 front and the male behind. The Anthldia 

 who make resin-dough and live in Snail- 

 shells can therefore alternate the sexes regu- 

 larly to meet the exigencies of the spiral 

 dwelling-house. 



One more thing and I have done. My ap- 

 paratus of reeds, fixed against the walls of 

 the garden, supplied me with a remarkable 

 nest of the Horned Osmia. The nest is es- 

 tablished in a bit of reed 1 1 millimetres^ wide 

 inside. It comprises thirteen cells and occu- 

 pies only half the cylinder although the ori- 

 fice is plugged with the usual stopper. The 

 laying therefore seems here to be complete. 



Well, this laying is arranged in a most 

 singular fashion. There is first, at a suitable 

 distance from the bottom or the node of the 

 reed, a transversal partition, perpendicular to 

 the axis of the tube. This marks off a cell of 

 unusual size, in which a female is lodged. 

 After that, in view of the excessive width of 

 the tunnel, which is too great for a series in 

 single file, the Osmia appears to alter her 



1.429 inch. — Translator's Note. 



153 



