342 Trans. Acad, Sci. of St. Louis 
CHAPTER II. 
Aw Amputator oF Sprpers’ Leas. Pseudagenia mellipes 
Say [S. A. Rohwer]. 
The genus Pseudagenia belongs to the family Psam- 
mocharidae, whose habits of nesting are in rather un- 
stable conditions, since each species shows peculiarities 
of its own. Natural selection has not, up to the present 
date, created fixed habits for the genus. There is, how- 
ever, one department in the work of this genus that has 
become rigidly established, that is the cutting off of the 
legs of the spiders stored as food for the young. All 
species whose habits have been studied show this trait, 
although in P. mellipes (fig. 37) it is possibly not so rigid 
as in other species, for in numerous cases I have found 
that only a part of a spider’s legs have been removed. 
As in the genus Trypoxylon, we find great versatility 
of behavior within certain species and within the genus. 
To Francis X. Williams* falls the credit of having 
brought to light some highly interesting behavior infor- 
mation on seven species of Pseudagenia which were stud- 
ied in the Philippine Islands, with the aid of which one 
can point out the evolution of the nesting behavior, from 
the simple, single mud cells of certain species to that 
masterpiece of economy, the work of P. mellipes. 
Versatility in behavior, or adaptability, seem to be the 
qualities which have led some individuals, at least, of 
P. mellipes to a method of nesting that is most economi- 
cal of labor, materials and time. In connection with the 
evolution of the nesting habits of Pseudagenia, the fol- 
lowing statement by Williams is indeed significant: ‘* The 
“Philippine Wasp Studies. Rept. Exp. Sta. Hawaiian Sugar Plant. 
Assoc., Bull. 14, pp. 79-108, 1919. 
