50 
The Food Relations of the Carabidce and Coccinellidce. 
ively, of food of animal origin. The excessively abundant Agon- 
oderus ranks but little higher as a carnivorous insect, fifteen 
examples having derived only about one-third of their food from 
animal sources. On the other hand, twenty-three specimens of 
Chkenius, and seventeen of Galerita had taken about nine-tenths 
of their food from insects, mites, myriapods and earth-worms. 
Thirteen specimens of Pterostichus had obtained three-fourths of 
theirs from similar sources, while Evarthrus and Calathus, repre- 
sented by seven and six specimens respectively, had averaged 
ninety-three per cent, and sixty-seven per cent. 
The fact has alreadv been alluded to that the Carabidae proper- 
had eaten only animal food, and that nearly all this was of a fluid 
character. 
Second, we find the Carabidae dividing into at least three tol- 
erably distinct groups as respects their food: first, those which 
seem usually to seize their prey and suck its juices, and take veg- 
etation rarely, if at all; second, those which take a much larger 
ratio of animal food than of vegetable, but masticate and swallow 
it, as a rule, including indigestible fragments; and third, those whose 
habit is essentially vegetarian, but which still take solid animal 
food in diminished ratios. A fourth group, consisting of Lebia 
and its allies, is perhaps obscurely indicated by the facts relating 
to the three specimens of Loxopeza atriventris studied. This 
will probably be found to feed largely upon pollen and fungus 
spores, after the manner of the Coccinellidm ; and the fossorial 
Carabidse will, perhaps, constitute a fifth. 
If we look now to the structures of these beetles for some 
explanation of their differences of habit, we shall find correspond- 
ing variations in the form and structure of the mandibles. Where 
the mandibles are long- and curved, and are destitute of basal 
molar processes, but are provided at or near the middle of the cut- 
ting edge with processes relatively long and sharp, the beetle seems 
to feed substantially upon soft or liquid animal food. If they are 
of medium length, somewhat slender, broad at base and tapering 
distally, with the tip acute, and provided with basal processes which 
are not especially prominent or sharp, the food is chiefly animal, But 
solid structures are masticated and swallowed, and some vegeta- 
tion appears in the alimentary canal; while, finally, if they are short 
and quadrate, blunt at the tips, and provided either with stroijg 
