Couplet 8

8a:  Hind femur and tibia narrow and subcylindrical in cross section; hind tarsus shorter than tibia and not tapered distally; body not streamlined, outline of thorax and elytron discontinuous, base of pronotum distinctly narrower than elytra; length 11-16 mm

Amphizoidae   p. 405

8b:  Hind femur and tibia more or less distinctly compressed, especially in larger species (length > 6 mm); hind tarsus usually as long or longer than tibia, distinctly tapering distally; body streamlined, outline of pronotum and elytron usually conjointly rounded (Figure 26-20A,C); length 1-40 mm