b. Legs not modified into clinging hooks; tibia and tarsus very long and slender; tibia without thumb-like process; antennæ five-segmented. Hæmatomyzidæ Endr.
Hæmatomyzus elephantis on the elephant.
bb. Legs modified into clinging hooks; tibia and tarsus usually short and stout; tibia with a thumb-like process; head not anteriorly prolonged, tube-like.
c. Body depressed; a pair of stigmata on the mesothorax, and abdominal segments three to eight; antennæ three to five-segmented.
d. Eyes large, projecting, distinctly pigmented; pharynx short and broad; fulturæ (inner skeleton of head) very strong and broad, with broad arms; proboscis short, scarcely attaining the thorax. Pediculidæ
e. Antennæ three-segmented. A few species occurring upon old world monkeys. Pedicinis Gerv.
ee. Antennæ five-segmented.
f. All legs stout; thumb-like process of the tibia very long and slender, beset with strong spines, fore legs stouter than the others; abdomen elongate, segments without lateral processes; the divided telson with a conical process posteriorly upon the ventral side. Pediculus L.
g. Upon man.
h. Each abdominal segment dorsally with from one to three more or less regular transverse rows of small setæ; antenna about as long as the width of the head. Head louse ([fig. 65]). P. humanus.