arT.13. DERMANYSSID MITES OF NORTH AMERICA—-EWING, 15 
second and third coxae, and expanded on the abdomen; setae as 
follows: A pair just behind anterior margin; another opposite second 
coxae; a third and fourth pair opposite third coxae; four pairs on 
broadened abdominal part of plate; an anal pair and a posterior 
median seta. Anus situated its greatest diameter in front of pos- 
terior margin of holoventral plate. Length, 0.44 mm.; width, 0.26 
mm. 
Type locality—(?) Germany. 
Type.—The location of the type is unknown to the author. 
This description is based on a specimen from the house mouse, 
taken at Corvallis, Oregon, January 9, 1912, by the writer. I can 
find no other record of the occurrence of this species in North Amer- 
ica. Exotic records are from Talpa, Mus, Vespertilio, Arvicola, and 
Pterygistes. 
ICHORONYSSUS ISABELLINUS (Oudemans). 
Female.—Body sparsely clothed with moderate setae. Dorsal 
shield covering all the body above except a narrow margin on the 
sides. Peritreme sinuous and extending as far as the anterior margin 
of the front coxae. Sternal plate archlike and continued between 
first and second coxae as cusps; anterior setae situated almost on the 
anterior margin; middle setae situated almost on the lateral margins; 
posterior setae situated near tip of produced posterior angles; all 
sternal setae long, slender, and subequal. Anal plate broadly rounded 
in front; anus almost circular, with rim somewhat thickened behind, 
and situated entirely in front of the middle transverse line; paired 
setae situated about halfway between the margin of anus and lateral 
margins of anal plate; anal area scobinate and extending about half- 
way to base of median seta. Longest dorsal spine of femur I about 
equal in length to width of this segment. Length, 0.66 mm.; width, 
0.32 mm. 
Male.—The writer has never seen a male of this species. The fol- 
lowing synopsis of characters is made from six good figures by 
Oudemans: Dorsal plate covering almost all of the upper surface of 
the body, sides almost straight, posterior margin rounded and at the 
tip of abdomen. Holoventral plate angularly produced between first 
and second coxae and second and third coxae, but not between third 
and fourth coxae, expanded slightly on the abdomen. All of the 
setae on the holoventral plate except the posterior median seta are 
arranged into two lateral irregular rows, there being four pairs on 
the sternal region and four on the abdominal region exclusive of the 
anal setae. Anus situated about twice its greatest diameter from 
the posterior margin of holoventral plate. Length, 0.50 mm.; width, 
0.34 mm. 
