Couplet 86

86a:  Antenna indistinctly to distinctly clubbed, apex received in margined cavity on posterolateral portion of hypomeron, just anterior to retracted fore leg; metasternum with or without oblique margined groove for mid tarsus; prosternum with click mechanism hidden by platelike ventral surface of postcoxal intercoxal process, which fits tightly against exposed portion of mesosternal cavity; elytra strongly striate and covered with silky, subrecumbent setae; abdomen with 5 connate ventrites; length 1-5 mm

Throscidae  p.422

86b:  Antenna variable (filiform, serrate, pectinate, etc.), but not clubbed; antennal groove, if present, at or near sternopleural suture; metasternum without margined groove for mid tarsus; if click mechanism hidden as in preceding entry, elytra not strongly striate and setae suberect; abdomen with 3 or 4 connate ventrites; length 1-60 mm (Figure 26-45A,C,D)

Elateridae  p.422