[ 3 r 4 ] 
bly larger and larger, 'in the fucceffive order of birds, 
till at length it conftitutes the whole of the organ; 
and the food keeps pace with this change, varying 
gradually from vegetable to animal. In one point 
of view, therefore, food may be confidered as a 
fir ft principle, with refpedt to which the digeftive 
powers, with their appendages, are as fecondary 
parts, being adapted to and determined by the 
food, as the primary object. 
We find then that in granivorous animals of all 
forts, there is an apparatus for the maflication of 
the food, although of different kinds and differently 
placed. But in true carnivorous animals of what- 
ever tribe, maflication is not neceffary, and there- 
fore they have no apparatus for that purpofe. 
The teeth of fuch quadrupeds, as are carnivorous, 
ierve chiefly to procure food and prepare it for 
deglutition. The fame thing holds in the true 
carnivorous bird, the office of whofe beak and ta- 
lons is to procure the aliment, and fit it for deglu- 
tition, correfponding in this refpeft to the teeth of 
the others. Applying this to fifh, it fee ms, at 
firft fight, that there is no occalion in them for 
that variety of ftrucfture in the digeftive organs, 
which is found in the beforementioned quadru- 
peds and birds ; the food of fifh being principally 
of one fort, namely, animal, which however with 
regard to the digeftive powers, is to be diftinguifhed 
into two kinds, viz. common foft fifh and fhell- 
fifh. Such fifh as live on the firft kind, have like 
the carnivorous quadrupeds and birds, no appa- 
ratus for maflication; their teeth being intended 
merely for catching the food and fitting it to hs 
fwallowed* 
7 
