THE OSMIiE 239 



tuberances on the forehead, the sign of the future armor 

 of the females. Well, the small cocoons, those in the 

 narrow front cells, with their scanty store of provisions, 

 all belong to males ; the big cocoons, those in the spacious 

 and well-stocked cells at the back, all belong to females. 



The conclusion is definite: the laying of the Three- 

 horned Osmla consists of two distinct groups, first a 

 group of females and then a group of males. 



With my pan-pipe apparatus displayed on the walls of 

 my enclosure and with old hurdle-reeds left lying flat out 

 of doors, I obtained the Horned Osmia in fair quantities. 

 I persuaded Latreille's Osmia to build her nest in reeds, 

 which she did with a zeal which T was far from expect- 

 ing. All that I had to do was to lay some reed-stumps 

 horizontally within her reach, in the immediate neigh- 

 borhood of her usual haunts, namely, the nests of the 

 Mason-bee of the Sheds. Lastly, I succeeded without 

 difificulty in making her build her nests in the privacy of 

 my study, with glass tubes for a house. The result sur- 

 passed my hopes. 



With both these Osmiae, the division of the gallery is 

 the same as with the Three-horned Osmia. At the back 

 are large cells with plentiful provisions and widely 

 spaced partitions; in front, small cells, with scanty pro- 

 visions and partitions close together. Also, the larger 

 cells supplied me with big cocoons and females; the 

 smaller cells gave me little cocoons and males. The con- 

 clusion therefore is exactly the same in the case of all 

 three Osmiae. 



These conclusions, as my notes show, apply likewise, 



