THE RELATIONSHIP OF THE DIFFERENT BROODS. 



As a rule the relationship of the broods in point of distribution 

 agrees with their kinship as indicated by their sequence in time of 

 appearance. The relationship indicated by the latter, viz, their 

 sequence in time, is doubtless untrustworthy as indicating origin, in 

 some instances, on account of the uncertainty arising from the action 

 of the principle of retardation on the one hand and acceleration on 

 the other in the forming of new broods. 



In the case of a widely scattered brood, like Brood VI, it is quite 

 possible that certain swarms originated from a later-appearing brood 

 by retardation of individuals, and other swarms froin an earlier 

 brood by acceleration in time of appearance of individuals. 



This same condition may be true of other of the more scattered 

 broods, but with the broods presenting a compact range a singleness 

 of origin is evident. 



Examination of the distribution of the broods in connection with 

 their sequence in time of appearance indicates, however, a certain 

 relationship between the different broods in point of origin, which 

 may be indicated as follows : 



THE RELATIONSHIP OF THE 17-YEAR BROODS. 



From the standpoint of distribution the broods of the 17-year race 

 may be grouped as follows: (1) Broods I and II; (2) Broods III and 

 IV- (3) Brood V; (4) Brood VI; (5) Broods VII, VIII, IX, X, and 

 XI; (G) Broods XII, XIII, XIV, and XV; (7) Broods XVI and 

 XVII, the last connecting again with Brood I. 



Taking up these broods in regular order : 



The main bod}^ of Brood I occupies territory immediately west of 

 the more important Brood II, and also presents a number of colonies 

 extending westward to Colorado. Broods I and II seem, therefore, 

 closely allied in point of origin. 



Brood III presents little, if any, relationship to Brood II in point 

 of location and distribution, but is closely allied to the following 

 brood, IV, and the latter is evidently a western and southern exten- 

 sion of III. 



Brood V presents little relationship with Brood IV in point of dis- 

 tril:)ution and covers a very compact territory. 



Brood VI, being a widel}^ scattered one, and occurring usually in 

 small numbers, does not seem to present any particular relationship 

 with any of the preceding or following broods. 



Brood VII is local in distribution and not very important, and is 

 divided into two sections by the territory occupied by the following 

 Brood VIII, with which it thus seems to be closely allied. Brood 

 IX is very distinctly a southern extension of Broods VII and VIII. 



