Couplet 7

7a:  Pedicel of antenna greatly enlarged, offset from main line of antenna, flagellum very short and compact, not extended beyond hind margin of head (Figure 26-5E); mid and hind legs very short (Figure 26-17B); eyes usually divided into 2 isolated parts on each side (Figure 26-17C), rarely with only a very narrow process (the canthus) extending between upper and lower portions.

Gyrinidae   p. 403

7b:  Pedicel of antenna normal, antenna extended beyond hind margin of head; mid and hind legs not especially short; eyes not divided.