Siphonaptera 
3 T 7 
gg. Antepygidial bristles five on each side; eyes absent; suture 
white. D. stylosus on rodents. Dolichopsyllus Baker 
ff. Labial palpi four or five-segmented; asymmetrical (membranous 
behind), apex acute. Hoplopsyllus anomalus found on Spermo- 
philes in Colorado . Hoplopsyllid^e 
ee. Pronotum without ctenidium. Anomiopsyllus californicus and 
nudatus on rodents . Anomiopsyllid.e 
cc. Very short fleas; flagellum of the antenna with pseudo-segments coales- 
cent; thorax much shorter than the head and than the first tergite 
. HECTOPSYLLID.E 
Flagellum of the antenna with six coalescent pseudo-segments; maxilla 
blunt. The chigger on man (fig. 93). D. penetrans. 
. (= Rhynchoprion = Sarcopsylla) Dermatophilus Guerin 
bb. Flagellum short, round, free portion of the first segment shaped like a 
mandolin. 
c. Thorax not shorter than the head, longer than the first tergite; flagellum 
either with free segments or in part with the segments coalescent. 
d. Head and pronotum with ctenidium; labial palpi asymmetrical. . . . 
. ARCHjEOPSYLLIDjE 
With four subfrontal, four genal, and one angular ctenidia. Widely 
distributed . Ctenocephalus Kol. 
e. Head rounded in front (fig. 92a). Dog flea . C. canis 
ee. Head long and flat (fig. 92b). Cat flea . C. felis 
dd. Neither head nor pronotum with ctenidium. Labial palpi asym¬ 
metrical, membranous behind . PULICID.® 
e. Mesosternite narrow, without internal rod-like thickening from the 
insertion of the coxae upwards. Human flea, etc.Pulex L. 
ee. Mesosternite broad with a rod-like internal thickening from the 
insertion of the coxae upwards (fig. 89). X. (Loemopsylla) cheopis, 
plague or rat flea. Xenopsylla 
cc. Thorax much shorter than the head and than the first tergite. Echi- 
dnophagidae. E. gallinacea, the hen flea also attacks man (fig. 96). 
.(= Argopsylla =Xestopsylla) Echidnophaga 011 iff_ 
