250 



MISSOURI BOTANICAL GARDEN. 



G 



r> 



+ 



o 



while the remaining nine regions from which Hymenoptera 



have been recorded average 



4.06. Turning to the total 



number of forms occurring in the several regions we find 



o 



+ 



'to 



to 



+ 



Conclusions concerning the distribution of the Hymen- 

 optera must bo only tentative since the vast order has been 

 very little investigated, even in its most highly specialized 



Apid 



The distribution by species need not 



be discussed in this place. 



The points of agreement of these several tables are too 

 apparent to need further comment. To facilitate com- 

 parison, the distribution of plants and insects has been 

 summarized in the form of percentage curves. A glance 

 at the accompanying diagrams, L and M, will make clear 

 the relative proportion of the different elements in the 

 flora and fauna and show the striking similarity between 

 the distribution of the apical ly dehiscent genera and the 

 Apidae. In this series of curves, the fourteen ordinates 

 represent the fourteen regions, and the percentage of 

 plants or insects endemic or occurring in a given region is 

 indicated on these by the curves. A is the curve for the 

 apically dehiscent forms, B for all genera; a for the 

 Apidae, and b for all Hymenoptera. The high percentage 

 of Apidae and other Hymenoptera in regions 10 to 14 is 

 doubtless to be accounted for by the greater thoroughness 

 with which these regions have been studied. 



Comparison of Distribution of Fauna and Flora. 



We seem to have in the data which have just been pre- 

 sented strong indications of a direct relation between the 

 geographical distribution of the Apidae and that of the 

 floral types which we have studied. 



It is somewhat surprising that so little has been done 

 towards the investigation of the distribution of floral 



