FURTHER DESCRIPTION OF POLY PL AX 
ALASKENSIS EWING (ANOPLURA) 1 
By W. B. Quay 
Biological Laboratories, Harvard University 
Polyplax alaskensis was first described by H. E. Ewing 
(1927, Proc. Ent. Soc. Wash., 29 : 118-121) from a single 
male taken from a mouse, Microtus sp., in Alaska. No 
subsequent collecting records of this species have been 
found in the literature. During the summer of 1948 a 
large series of individuals of both sexes was secured from 
mice, Microtus o. operarius (Nelson), collected on the 
Seward Peninsula by the writer. Since the original de- 
scription is brief and unfigured, I am including here a 
further description of the species based on the numerous 
specimens now at hand. 
Acknowledgments are made to J. C. Bequaert of the 
Museum of Comparative Zoology and to Floyd G. Werner 
of the Harvard Biological Laboratories for aid and ad- 
vice. I am also very grateful to C. F. W. Muesebeck of 
the Bureau of Entomology and Plant Quarantine, U. S. 
Department of Agriculture, for corroborating the identi- 
fication by comparing a specimen from my series with 
the type. 
Female (Fig. 1, A). Length 1. 2-1.4 mm. Head al- 
most as broad as long and generally similar to that of 
spinulosa ; first antenna joint much longer than the others 
and set close to the anterior margin. Thorax dorsally 
similar to that of spinulosa ; ventrally, the sternal plate 
is longer than it is broad; the anterior lateral margins 
are nearly parallel ; the posterior lateral margins are con- 
cave and slope to a blunt point ; the legs, of usual form, 
are of increasing size posteriorly. 
Pleural plates : (Fig. 2, B) first pleurite elongate, 
faintly if at all chitinized medially and usually with three 
1 Published with a grant from the Museum of Comparative Zoology at 
Harvard College. 
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