hh. "No transverse rows of abdominal setæ; antenna longer than the width of the head; species larger." Piaget. Body louse of man. P. corporis.
gg. Upon apes and other mammals. P. pusitatus (?).
ff. Fore legs delicate, with very long and slender claws; other legs very stout with short and stout claws; thumb-like process of the tibia short and stout; abdomen very short and broad; segment one to five closely crowded, thus the stigmata of segments three to five apparently lying in one segment; segments five to eight with lateral processes; telson without lateral conical appendages ([fig. 69]). Crab louse of man. Phthirus pubis.
dd. Eyes indistinct or wanting; pharynx long and slender, fulturæ very slender and closely applied to the pharynx; proboscis very long. Several genera found upon various mammals. Hæmatopinidæ.
cc. Body swollen; meso- and metathorax, and abdominal segments two to eight each with a pair of stigmata; eyes wanting; antennæ four or five-segmented; body covered with stout spines. Three genera found upon marine mammals. Echinophthiriidæ
aa. Legs fitted for walking or jumping; spiracles of abdomen usually ventral; beak segmented.
b. Apex of head usually directed anteriorly; beak arising from its apex; sides of the face remote from the front coxæ; first pair of wings when present thickened at base, with thinner margins. HETEROPTERA
c. Front tarsi of one segment, spade-form (palæformes); beak short, at most two-segmented; intermediate legs long, slender; posterior pair adapted for swimming. Corixidæ
cc. Front tarsi rarely one-segmented, never spade-form; beak free, at least three-segmented.
d. Pulvilli wanting.