STRUCTURE. 
235 
it is irregularly clubbed (Hydrophilidce ); in 9, it is incompletely clubbed, 
with the leaflets not forming a compact mass ( Lucanidce ). 
Fig. 135.— LUCANID BEETLE, MALE, DORSAL VIEW. MD., MANDIBLE; PROTH., 
PROTHORAX; SCUT., SCUTELLUM ; ELYT., ELYTRON ; PYG., PYGIDIUM. 
The tarsi are composed of five joints in some forms, of four or three 
in others; in one division ( Heteromera ) the tarsi of the first two pairs of 
legs are five-jointed, of the third pair, four-jointed. In the Phytophaga 
the tarsi appear to be four-jointed, the tiny fourth joint being invisible 
at the base of the fifth. 
There are characteristic features in the immature stages which mark 
the group as a whole. Eggs are of two types, the soft oval eggs laid in 
concealment, the harder variously-shaped eggs laid openly. The latter 
are not ornamented as are those of the Lepidoptera, are not of the form 
characteristic of Hemiptera with lids, nor of the typical Dipterous cigar¬ 
shaped form. The larvae are without suckerfeet, and if free-living, 
frequently have the single anal tube, which functions as a suckerfoot, as 
