Complex sentence: The second defining characteristic of the Cleridae family is that Clerids never have eversible vesicles (small usually hidden balloon-like structures thought to be scent glands) on their abdomen and pronotum; this distinguishes them from a similar family Melyridae which sometimes has these glands.
Split into simpler sentences: The second defining characteristic of the Cleridae family is that Clerids never have eversible vesicles (small usually hidden balloon-like structures thought to be scent glands) on their abdomen and pronotum. This characteristic distinguishes them from a similar family Melyridae which sometimes has these glands.