A NEW SPECIES OF PSEN. 
By Henry L. VierEck. 
Psen (Mimesa) barthi n. sp. 
Wings brownish transparent, nervures and stigma dark brown. 
Belongs to Fox's group Kohli, but clypeus subbidentate. 
Female. 10 mm. Head : Pretty much the same as in sitnpUci- 
cornis; polished portions with a steel blue reflection. 
Thorax : Dorsulum approximately as in simpUcicornis ; scutel 
punctured and striate ; mesopleura distinctly but sparsely punctured ; 
dorsulum and mesopleura with a steel blue reflection; knees black, 
spurs whitish, tarsi brownish testaceous to brown ; otherwise as in 
simpUcicornis. 
Abdomen : Pygidium bounded by a distinct carina; otherwise as 
in simpUcicornis. 
Barring the exceptions already alluded to, this insect is almost 
uniformly black. 
Type Public Museum, Milwaukee, Wis. Type locality, Mil- 
waukee, Wis. One specimen collected by Dr. Geo. P. Barth. 
ON THE NESTING HABITS OF PSBN BARTHI VIERECK 
By George P. Barth. 
Revenge is sweet. This spirit may have tinged the feeling of 
satisfaction which was derived from demolishing the abiding place 
of the above described intruder on what I fondly regarded as my 
crabro preserve. During the years 1905 and 1906 this old log 
in Bradley's Woods, on the Milwaukee- Waukesha County line, 
had been a continuous source of pleasure and profit to me in my 
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