ART. 13. DERMANYSSID MITES OF NORTH AMERICA——-EWING, 23 
uated halfway from rim of anus to lateral margins of plate; caudal 
area small, scobinate. Legs large; first and last pair subequal and 
longer than the two other pairs. Length, 0.72 mm.; width 0.41 mm. 
Male.—Smaller than the female and more slender, especially in 
the abdominal region. Chelicerae stout; fixed arm longer than mov- 
able, doubly curved and with an inner toothlike protuberance. Dor- 
sal shield similar to that of the female. Holoventral plate widest at 
its angular expansions between the second and third coxae, on the 
abdomen first slightly expanded then much narrowed in front of 
anus. Holoventral plate with the usual setae on sternal region, but 
on the abdominal region, with only two marginal pairs except for 
the anal pair and posterior median seta. Anus oval in outline and 
situated about twice its greatest diameter in front of posterior mar- 
gin of holoventral plate. Length, 0.61 mm.; width, 0.29 mm. 
Type locality.—Buenos Aires, Argentina. 
Type.—(%) Not selected in original description. 
North American records as follows: On chickens (Dallas Lab. ace. 
2568); on poultry, Atlantic Beach, Florida, June, 1915; infesting 
house, North White Plains, New York, June, 1911; on porch of 
house, near Ottowa, Canada; on common hen, Canal Zone, Doctor 
Darling (No. 157); on chickens, Winter Park, Florida (Dallas acc. 
2507); on poultry, Beltsville, Maryland, April 2, 1917; on poultry, 
Raymond, Illinois, 1919, by H. P. Wood; on poultry, Lafayette, 
Indiana, October 19 and 24, 1921. 
Genus DERMANYSSUS Dugés. 
KEY TO NORTH AMERICAN SPECIES. 
a‘. Peritreme long and sinuous, extending beyond the second coxae. 
D. gallinae (Redi). 
a*. Peritreme short, broad, and almost straight, and not extending beyond the third 
oo OT, Se ee es SERS neers Oy none D. americanus, new species. 
DERMANYSSUS GALLINAE (Redi). 
Female.—Considerably larger than male. Palpi reaching the tips 
of femora of anterior legs; chelicera apparently with both arms 
present but each is needlelike, and the two fit together to form a 
single piercing structure. Dorsal shield large, convex behind the 
shoulders, and almost truncate behind. Peritreme with a slight 
bulb near stigma; extending to between coxae I and II. Sternal 
plate a transverse band of chitin passing between the anterior aspects 
of the second coxae but also reaching the first coxae; it is about 
four times as broad as long and bears a single pair of setae situated 
just behind the anterior margin. Anal plate with almost straight 
anterior margin; anus with greatest diameter longitudinally, rim 
thin except behind, where it is very thick, paired setae about twice 
