b. Flagellum of the antennæ long and oval.
c. Usually elongate fleas, with a free-segmented flagellum of the antenna; thorax not shorter than the head, longer than the first tergite.
d. Genæ of the head and the pronotum with ctenidia. Neopsyllidæ
e. Labial palpi four or five-segmented; symmetrical; hind coxæ with patch of spines inside; row of six spatulate spines on each side in front of the antennæ. C. ornate found on a California mole. Corypsylla
ee. Labial palpi two-segmented, transparent, membranous. On hares. Spilopsyllus Baker
dd. No ctenidium on the head.
e. Pronotum with ctenidium. Dolichopsyllidæ
f. Labial palpi five-segmented, symmetrical.
g. Antepygidial bristles one to three; eyes present.
h. Inner side of hind coxæ distally with a comb of minute teeth; falx present. On rodents and carnivores. Odontopsyllus Baker