488 PEALE’S EGRET HERON. 
they have but one cecum, like quadrupeds, while other birds 
have two. The genus Ardea is admitted by all authors, 
though some modern writers have cut it up into several, 
which we employ as subgenera, or groups of still minor 
importance. Generally divided into three, and by Boie into 
five, they might with the same propriety be carried to seven 
or eight. We recognise no more than three, comprising eight 
secondary groups. ‘The first, which we call more properly 
heron (Ardea), is well distinguished by its long and slender — 
neck, all well clothed with shortish oppressed feathers, and by 
having a very large part of the tibia naked. 
The second, called bittern (Botawrws), has the neck shortish, 
with loose, longish feathers, and the posterior more or less 
distichous and lanuginous: the naked part of the tibia is 
much limited. 
In all the herons the bill is more or less longer than the 
head, cleft to beneath the eyes, straight, compressed, conic-elon- 
cate, acuminate, and very acute, higher than wide, and more 
or less robust. Both mandibles are near their base covered 
with a kind of very thin cere or membrane: the upper is 
scarcely longer than the lower mandible, and equal in height: 
it is longitudinally impressed on the sides with a straight 
furrow obliterated before: the upper ridge is therefore rather 
distinct and flat at base, terminated by the frontal feathers 
transversely placed ; towards the point the ridge is perfectly 
smooth, compressed, and slightly and gradually inclined at 
tip: the edges, nearly vertical, in some species are perfectly 
entire, in others obliquely and finely denticulated, in all emar- 
cinated at the extreme tip: the palate has in the middle 
a longitudinal sword-like process, perfectly straight, which 
towards the throat is more or less conspicuously doubled : the 
lower mandible has strong and flattened sides, more or less 
impressed towards the base ; it is sharply acute, with the edges 
drawn in, excessively sharp, quite straight, either entire or 
slightly serrated obliquely : the inferior ridge is slightly com- 
pressed, rather acute, and more or less ascending ; the mental 
