The Distribution of the Sexes 



2. A series of nine: three females first, 

 then six males. 



3. A series of eight: five females followed 

 by three males. 



4. A series of eight : seven females fol- 

 lov^'ed by one male. 



5. A series of eight: one female followed 

 by seven males. 



6. A series of seven: six females followed 

 by one male. 



The first series might very well be com- 

 plete. The second and fifth appear to be the 

 end of layings, of which the beginning has 

 taken place elsewhere, In another bramble- 

 stump. The males predominate and finish 

 off the series. Nos. 3, 4 and 6, on the other 

 hand, look like the beginning of layings: the 

 females predominate and are at the head of 

 the series. Even if these interpretations 

 should be open to doubt, one result at least 

 is certain : with O. dclrita, the laying is 

 divided into two groups, with no interming- 

 ling of the sexes; the first group laid 

 yields nothing but females, the second or more 

 recent yields nothing but males. 



What was only a sort of attempt with the 

 Thrcc-prongcd Osmia — who, It is true, begins 



99 



