110 
Psyche 
[June 
determination. One very unusual species ( reductus ) from 
this lot has already been described 2 . Quite recently, also, 
Mr. L. C. Lloyd has described 3 another species ( inter- 
medins) from Alaska, and recorded the occurrence of B. uni- 
color at the same locality. Through the courtesy of Mr. Lloyd 
and the authorities of the Washington State Museum, these 
specimens were sent to me for examination. Much to my 
surprise, a study of all the Boreus material now at hand re- 
veals that among the recently collected Western material 
there are no less than five undescribed species, making a 
total of twelve species of the genus now known from the 
Nearctic region. 
These additional species have brought to light several new 
characteristics which are most useful in the taxonomy of 
at least the Nearctic members of Boreus. The most impor- 
tant of these is the form of the hypandrium (tenth sternite) , 
which may be either narrowly or broadly triangular, and 
may be either emarginate (notched) or entire (straight). 
Since the shape of the hypandrium is very helpful in the 
identification of the new species described below, I have also 
included here figures or descriptions of other Nearctic spe- 
cies of the genus. Some of the new species are also charac- 
terized by the color and length of the pubescence, features 
which show very little difference among 1 the previously de- 
scribed ones. The lengths of the rostrum and ovipositor are 
likewise convenient diagnostic characteristics, but I have 
found it advisable to measure these at somewhat different 
positions from formerly. In the present descriptions the ros- 
trum is measured from the ventral edge of the eye, and the 
ovipositor from the posterior margin of the ninth tergite 4 . 
This gives a slightly smaller dimension for the length of the 
ovipositor than when it is measured from the corresponding 
sternite, but the measurement is more easily obtained since 
the specimens are usually glued to points and the ventral 
surface of the head thus concealed. The detailed coloring of 
the various parts of the body, as I have already pointed 
2 Can. Ent., 65: 94-95. 1932. 
s Pan. Pacific Ent., 10: 119-120. 1934. 
4 the ninth tergite because the tenth is modified to form a long 
sheath covering the ovipositor proper. 
