120 
Psyche 
[August-October 
different hosts with which their size and flight are correlated. 
Natural selection clearly favors this diversification. My view is 
that the inquilines separated first and got their specific differences 
afterwards. 
An inquiline producing mutants infesting the same host 
could not produce more individuals and could not become the 
basis of new evolution any more than one which did not produce 
them. 
As regards species in general I hold that everyone has selec- 
tive characteristics, holds its own bionomic position, and is the 
result of natural selection. 
Note on Sphecodini . — According to Schuckard (7, 108), St. 
Fargeau, Westwood and Latreille regarded these bees as inqui- 
lines, while Kirby and Smith regarded them as nest-makers. 
Mueller (9, 50) says they feed their young with the disgorged 
surplus of their own food. 
Literature Cited. 
1. Frison, T. H. 1916. Note on the habits of Psithyrus varia- 
hilis. Bull Brook. Ent. Soc. 11: 46-7. 
2. Graenicher, S. 1905. Some observations on the life history 
and habits of parasitic bees. Bull. Wis. N. H. Soc. 3: 
153-67. 
3 , 1906. A contribution to our knowledge of the 
visual memory of bees. Bull. Wis. N. H. Soc. 4: 138-9. 
4. Robertson, C. 1899. On the flower visits of oligotropic bees. 
Flowers and insects XIX. Bot. Gaz. 26: 27-37. 
5 , 1899. Flower visits of oligotropic bees. Bot. Gaz. 
28: 215. 
6 . , 1924. Phenology of anthophilous insects. Flower 
visits of insects II. Psyche 31: 93-111. 
7. Shuckard, W. E. 1866. British bees. 
8. Swenk, M. F. 1914. Studies of North American bees. 
University Studies. Lincoln Nebr. 14: 1-36. 
9. Mueller, H. 1883. Fertilisation of flowers. 
