50 The Food Relatione of the Carabidce and C'occinellidce. 



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 

 Chla?nius, and seventeen of Galerita had taken about nine-tenths 

 of their food from insects, mites, myriapods and earth- w^orms. 

 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 already been alluded to that the Carabidfe proper 

 had eaten only animal food, and that nearly all this was of a fluid 

 character. 



Second, we find the Carabidje dividinof 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 JLoxopeza atriventris studied. This 

 will probably be found to feed largely upon pollen and fungus 

 spores, after the manner of the Coccinellida' ; and the fossorial 

 Carabida? will, perhaps, constitute a fifth. 



If we look now \f> 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 strong 



