The Food Relations of the Carabidce and Coccinellidce. 
56 
especially as no comparison whatever was made of the two 
sets of data until the tables were completed in their present form. 
When, therefore, we find that the one hundred and seventy-five 
specimens of the present paper, belonging to thirty-eight species, 
were estimated to have taken fifty-seven per cent, of animal food 
and thirty-six of insects, and that the ratios of cryptogams, gram- 
inaceous plants and exogens are respectively five, eleven, and five, 
we must conclude that these figures are a fair average of the 
ordinary food of the family. 
Relations to Birds. 
The foregoing pages have set forth the relations of the Carab- 
idse and the Coccinellidie to the species upon which they feed, 
and a few general statements will now be proper concerning the ani- 
mals which prey upon them in turn. Predaceous ground-beetles 
are peculiarly exposed to birds which commonly seek their food upon 
the ground, and we need not be surprised to find that they enter 
largely into the food of such species as the thrushes and the blue- 
bird. Carabidae were found to furnish about five or six per cent, 
of the food of four hundred and twenty-three specimens of these 
birds, as stated in a paper on that subject in the third Bulletin of 
this series, but Coccinellidae did not occur at all. Indeed, in the 
food of more than four hundred other birds, of various families, 
Ooccinellidae were found only in Regulus, where a single species 
was reckoned at one per cent, of the food. 
The great differences in the food of the Carabid;e, disclosed by 
this paper, give considerable importance to the question of the 
kinds of these beetles most freely eaten by birds, and the follow- 
ing list of species and genera recognized in the food of the col- 
lection of thrushes and bluebirds above mentioned is given as an 
answer. 
It will be seen that there is a very wide difference between the 
number of Carabidas proper taken by these birds, and the number 
of Harpalidae, representatives of the former group occurring in 
only six specimens, and of the latter in one hundred and sixteen. 
On the other hand, fifty-nine of the birds had taken Harpalids 
which may be fairly classed with the second group established in 
this paper, and fifty-seven had taken those belonging to the third 
group, or phytophagous Carabidae. The genera most preyed 
