This family is of small extent, and the members are as a rule easily recognized by their peculiar habits. In the genera Lucanus, Dorcus, Platycerus and Ceruchus the males are marked by a greater development of the mandibles, associated in turn with a greater or less broadening of the head. The antennæ differ from those of the Scarabæidæ (to which family the Lucanidæ are closely allied) in not having the plates of the club completely opposable. In other words the club is pectinate rather than lamellate. These organs offer a good character for the division of the family into two divisions—the first containing those genera in which the antennæ are geniculate (i. e., crooked like a bent knee, the second and following joints forming an angle with the first, as shown in the figure of Lucanus dama, fig. 12), while the second is composed of those in which they are straight. The male antennæ frequently differ from those of the female, but it is not necessary to enter into details for the purpose of this paper.