1949] 
Quay — Polyplax 
183 
chitinized. First three sternites are strongly convex an- 
teriorly and are quite long ; the third is much longer than 
the other two and the central area of its anterior margin 
is produced into a pointed lobe limited laterally by the 
base of a large seta ; the greatest length of the third ster- 
nite distinctly exceeds that of the fourth and is about half 
that of the following four sternites ; all five have roughly 
parallel and straight anterior and posterior borders. 
Genitalia (Fig. 2, A) as described by Ewing and fig- 
ured here. 
Figure 2. Polyplax alasTcensis. A. Genitalia of males: bp, basal plate; 
pm, parameres; pp, pseudopenis (also shown in oblique view). B. Pleural 
plates of female (setae of the sixth and seventh are abbreviated). 
Specimens examined: twenty-four of both sexes and 
different ages, collected at Cloud Lake (near Asses Ears), 
Seward Peninsula, Alaska, July 27, 1948. Representa- 
tive specimens have been deposited in the collections of 
the Museum of Comparative Zoology and the National 
Museum. 
