228 Trans. Acad. Sci. of St. Louis 
manner of a parasite, I think much doubt as to its habits 
is removed. This of course would mean that P. inter- 
rupta, having at some time been derived from the genus 
Anthophora has found a way to escape the Anthophora 
responsibilities of mining and food gathering by turn- 
ing parasitic on its own kin, just as seems to be the 
case with Psithyrus in the nest of Bombus. 
Mutillids. The cow-killers or velvet ants, with wing- 
less females and winged males, are well known to be 
parasitic, and their way of prowling about the clay bank 
indicates that, like many of our own species, seeking 
hosts is the sole ambition of their lives. They undoubt- 
edly found hosts in the clay bank. 
Dasymutilla ferrugata Fab. [S. A. Rohwer]. On June 
28, 1917, one female was seen to enter a dozen 
burrows of the Anthophora bee, and in some it remained 
a sufficiently long time to have done mischief. Other 
mutillid parasites, which remained unidentified, were 
seen doing precisely the same on July 31, and August 10. 
Sphaerophthalma scaeva. Two females of this para- 
site were darting about as if on mischief bent, on Au- 
gust 30, and on the next day a half-dozen or more were 
seen. We have previously reared these parasites from 
the old nests of the mud-dauber, Sceliphron caementar- 
qum., 
On the clay bank, besides D. ferrugata and S. scaeva, 
one would occasionally pick up an unknown specimen of 
the Mutillids; I suspect that they were seeking hosts, 
but their numbers were so insignificant in comparison 
to the other parasites that I do not think they were to 
be regarded as a ‘‘real force in the community.”’ 
Sphaerophthalma pennsylvanica Lep. [S. A. Rob- 
wer]. A small elm shrub, between the clay bank and 
