Series 4. Heteromera.—Front and middle tarsi five-jointed, hind tarsi four-jointed. Other characters very variable.
Series 5. Phytophaga.—Tarsi four-jointed [apparently], but with a small additional joint at the base of the fourth joint: sole usually densely pubescent [sometimes the feet are bare beneath or bristly, and occasionally the small joint at the base of the fourth joint is more distinct].
Series 6. Rhynchophora.—Head prolonged in front to form a beak; gula indistinguishable. [Palpi usually not evident.] Tarsi four-jointed [apparently], but with a very minute additional joint at the extreme base of the fourth joint.
Strepsiptera (see p. [298]).
The first and second series, with much of the third, form the Pentamera, the fifth and sixth the Tetramera [or Pseudotetramera[[78]]]. The term Isomera was applied by Leconte and Horn to a combination of series 1, 2, 3, and 5.
Series 1. Lamellicornia.
Tarsi five-jointed; antennae with the terminal joints (usually three, sometimes more), broader on one side, so as to form a peculiar club, the leaves of which are movable, and in repose are more or less perfectly coadapted so as to have the appearance of being but one piece.
This series includes three families, Passalidae, Lucanidae, and Scarabaeidae; the latter includes an enormous majority of the species, and in them the structure of the antennae characteristic of the series is well developed; but in the other two families the form of the antennae is not so widely different from that of other Coleoptera. The larvae live on decaying vegetable matter, roots or dung. They have three pairs of legs, and are thick clumsy grubs with curved bodies, the last two segments being of larger size than usual. Many of them possess organs of stridulation, and the structure of their spiracles is very peculiar, each one being more or less completely surrounded by a chitinous plate. The spiracles usually form a system entirely closed, except at the moment when the skin is shed and the tracheal exuviae are detached. Meinert[[79]] considers these spiracles to be organs of hearing. The life of the larvae is passed underground or in the decaying wood on which the Insect feeds.
Fig. 85.—Antennae of Lamellicorns. 1, Neleus interruptus; 2, Lucanus cervus ♂; 3, Phanaeus splendidulus ♀; 4, Phileurus didymus ♀; 5, Polyphylla fullo ♂.