46 The Food Relations of the Carabidie and Cocc'mellidK. 



ordinary situations, consisted of animal food, of which a little less 

 than half was insects. Fungi made thirteen per cent., and the 

 remaining vegetable food was about equally divided between 

 grasses and exogenous plants. Three specimens of H. caluiirio- 

 sus and If. pennsylvanicus., taken among the canker-worms, had 

 derived one-third of their food from those caterpillars, while the 

 other two-thirds consisted of vegetation, sixteen per cent, being 

 Penjuospora, and the remainder chiefly seeds and exogenous 

 tissues. Four specimens of //. herbivagus, collected in the cab- 

 bage field, in April, had eaten none of the cabbage-worms, and 

 only ten per cent, of insects (Diptera). The remainder of the 

 food consisted apparently of fragments of seeds, as indicated by 

 the contents of the cells of the fragments and by other micro- 

 scopic characters. A piece of the epidermis of grass was noticed 

 in one of the beetles. Taking the genus Harpalus as a whole, as 

 far as these nineteen specimens can be supposed to indicate its 

 food, we find that only about one-eighth of it consisted of animal 

 substances. Insects stand at nine per cent., two-thirds of them 

 caterpillars, — ants and Diptera making up the balance. Among 

 the items on the vegetable side of the account, we find funsfi and 

 pollen of Comp(jsitae each eleven per cent, and seeds and other 

 tissues of grasses, fourteen per cent. 



Genus Patkobus. 



Two specimens of P. loiujicornis., one from Central and the 

 other from Southern Illinois, had eaten nearly twice as much 

 vegetation as animal food. The latter consisted chiefly of cater- 

 pillars, and included in fact nothing else but traces of plant-lice, 

 eaten by one of the two. A little of the vegetation was derived 

 from trrass, but the source of the remainder could not be satisfac- 

 torily traced. 



The Family as a Unit. 



We have now to treat the various collections of Carabidas upon 

 which this paper is based, as distinct and unbroken groups, with- 

 out reference to the genera of which they are composed. The 

 eighty-three specimens of all the species obtained in miscellane- 

 ous situations, are found to have derived forty-two per cent, of 

 their food from the animal kingdom, while the seventy specimens 



