a case of persistent melanism. 227 



Mating Statistics. 

 Having been foiled in my attempts at breeding these beetles, 

 I decided to attack the problem from a different standpoint, 

 namely, to observe the mating habits in nature, to see if the 

 black individuals mated as freely with the red ones as with 

 those of their own. color. During the months of May and June 

 I made fourteen different observational trips to some patches of 

 wild roses at the west end of the town of Corvallis, Oregon. I 

 collected every pair that was observed mating, as well as those 

 that were not observed mating; these were collected so as to 

 obtain population statistics. The results obtained were as 

 follows: ~^~^ 



Total number of matings observed 53 



Normal Rhynchites bicolor X normal Rhynchites bicolor 44 



Melanic form X melanic form 



Normal R. bicolor cf X melanic form 9 3 



Melanic cf X normal R. bicolor 9 9 



Thus we find that out of the total number of matings observed 

 in nature, 83 per cent, were between normally colored individuals, 

 while 16 per cent, were between melanic individuals and normal 

 ones; no matings being observed between two melanic forms. 



Although we can not prove anything in regard to the exact 

 status of these two forms of Rhynchites from these observations 

 alone, yet we may speculate, somewhat, in regard to a few points. 

 They tend to indicate: 



1. That the normal intergeneration of these two forms is 

 followed by the segregation of the characters following the 

 dominance in the first cross. 



2. That the black form is recessive to the red. 



3. That racial characters have become fixed without natural 

 barriers, without isolation of any kind or without change of 

 habit but purely through the segregation of the characters in 

 the germ plasm. 



Population Statistics. 

 The population statistics obtained for the same patches of 

 wild roses that the mating statistics were obtained from, and 

 at the same time are as follows: 



