1883.] On the Genealogy of the Insects. 939 
than those of any other families. This ancestral Coleopterous 
larva was probably directly related to the Campodea-form ances- 
tor of the Hexapoda. The general form of the body, the 
homonomous segments, the free, biting, toothed mandibles, the 
well-developed one or two-lobed maxilla with their three-jointed 
palpi, and the well developed second maxillz (labium), also the 
four-jointed antennz, and the presence of ocelli, while showing 
that the existing carnivorous larvae are the most specialized and 
highly developed, also show that they have undergone the least 
modification from the primitive type of Coleopterous larva. In 
the scavenger larval forms, as the Silphide, Dermestide and 
allied families, the mouth-parts begin to be modified and less de- 
veloped, and the form of the body undergoes a change, becom- 
ing thicker and with less developed feet. 
In the Elateridæ and Scarabeidz, which in general are phyto- 
phagous, we see a still more decided change; the body becoming 
cylindrical and the mouth-parts more aberrant. 
In the wood-boring Buprestidae and Cerambycidz, and in the 
leaf-eating Chrysomelid larva, we witness a decided departure 
rom the carnivorous type; the mouth-parts show a tendency to 
become more or less aborted, the legs are frequently wanting and 
the body more or less maggot-like. Finally, the tendency to a 
gradual degradation and atrophy of the head, mouth-parts and 
legs culminates in the grubs of the weevils (Curculionidz and 
Scolytidze), placing them at the foot of the Coleopterous series), 
and shows that they have undergone the greatest modification of 
form, and have become adapted to conditions the most unlike 
those which constituted the environment of the primitive Coleop- 
terous larva. 
The relative form of the maxilla appears to be a good index 
as to the general development of the body in the different groups 
of Coleoptera, especially those standing above the wood-boring 
families. The facts may, for convenience, be arranged in the fol- 
lowing form : 
Cicindelide—Maxilla with a maxillary lobe or mala proper 
ending in a two-jointed appendage which is longer than the 
three-jointed palpus. (Antenne four-jointed ; three ocelli.) 
~ Carabide.—Maxilla with the mala two-jointed; maxillary pal- 
Pus four-jointed. (Antenne four-jointed, bifurcate ; ocelli often 
VOL, XVIL—NO. 1x, 63 
