26 
LOUSE OF THE WHITE FOOTED MOUSE. 
(Hcematopinus hesperomydis, n. sp.) 
Body elongate, general color golden yellow. 
Female. — Head snbquadrate, rounded in front, a concavity 
^y j for the rostrum, obtusely angulated on the posterior border; 
ffyjy antenna? set near the front ; first joint large, short ; second 
longest, the rest nearly equal; fourth with a small tooth on 
j the posterior border, terminal pit with several short hairs. 
Thorax shorter than the head, small, sternal plate cuneiform, 
obtusely angular, irregularly or obliquely truncate in front and 
sharply pointed behind ; anterior legs small and weak, the 
middle ones somewhat larger, the posterior pair much the 
largest, flattened ; terminal joint of tarsus very broad and 
curved, opposing basal joint of tarsus and meeting tibial spur 
in such manner that the three form almost a complete cylin- 
Fig. 14. Hcematopinus ^ GT . ak^on^n 0V al elongate, sparsely set with short spiny 
hesperomydis — a, dorsal ,. , , . , , , . , - . ,. , 
view; 6, head; c, sternal hairs > one or tw0 lon S' nairs at lateral angles of sixth and 
plate- d, posterior leg; e, seventh segments. 
terminal segments, male; Male, more slender, head longer and tapering somewhat 
all enlarged. (Original.) toward the front. See Fig. 14. 
Egg, as seen in the body of adult female specimen, is elongate oval. 
Millimetres. 
Length 75 i o .90 
Width 28 to .33 
Head: 
Length 13 to .16 
Width .10 
Thorax : 
Length . .10 
Width 13 to .15 
Abdomen : 
Length 50 to .60 
Width 28 to .33 
The species approaches the acanthopus, resembling it in the form of 
the sternal plate, the character of the legs, and the general form of the 
body. It differs, however, in having the sternal plate less narrowed 
posteriorly, more obtuse, or even truncated in front ; more decidedly 
still in the form of the head, which is longer and less excavated for the 
insertion of the antennae. It is also smaller, and the egg, if we may 
judge by what we can see through the walls of the female, is more 
elongated. 
It has been collected from the white-footed or deer mouse, Hesperomys 
leucopas, at Ames, Iowa. 
