546 
PICARIAN BIRDS. 
white eggs in an open nest, while humming-birds, which are also Picarian, likewise 
build an open nest and lay white or light-coloured eggs. No definite rule can be 
laid down as to the nesting of the Picarians, and there are further exceptions, 
though of a modified kind, and capable of a different explanation, such as occur 
in the case of the cuckoos, some of which lay white eggs, and others variegated 
and coloured ones. Although, in addition to the above not very important 
features, there are certain osteological characters peculiar to the Picarians, 
such as the form of the upper arm-bone or humerus, which exhibits well-marked 
differences from the corresponding bone of the perching birds, the definition 
of the order by means of well-marked and exclusive features is by no means easy. 
The palate is sometimes of the so-called segithognathous type, and at others of 
the bridged or desmognathous form; while the structure of the foot is variable 
in every degree, some Picarians having a foot in which the fourth toe is directed 
backwards, while in others the foot has the front toes joined together, so as to form 
a very flat perching surface. The Picarians may be divided into three chief 
sections, which may be called Scansores, or climbing Picarians; Coccyges, or cuckoo¬ 
like Picarians; and Coraciiformes, or roller-like Picarians; the chief differences 
between these groups occurring in the arrangement of the tendons of the feet, which 
need not be explained in a work of the present nature. 
The Jacamars. 
Family GalbulIDJE. 
Commencing with the climbing section of the order, our first representatives 
are the South American jacamars, of which about twenty species are known. All 
these birds have the so-called zygodactyle type of foot, in which the fourth toe is 
directed backwards parallel to the first. The bill is peculiarly long and straight; 
there is an aftershaft to the body-feathers, which does not occur in the allied group 
of the puff-birds; and there are some further differences in the arrangement of the 
feathers of the under surface, the tract on the breast having a branch on the throat. 
The number of tail-feathers varies in a somewhat peculiar manner, the normal 
number being twelve, but in two genera out of the six ( Brachygalba and Jaca- 
marcdcyon ) the outer feather on each side is wanting, thus reducing the number 
of feathers to ten. Although nothing absolutely decisive is known as to the 
breeding-habits of the jacamars, it is stated that in Tobago they build in holes in 
mud-banks, like the motmots, and lay pure white and nearly spherical eggs; while 
the three-toed Brazilian jacamar has been seen boring holes in banks as if for the 
purpose of nesting. 
True Jacamars. 
Together with four other genera of the family, the true jacamars 
constitute a subfamily group ; Galbula and the allied genus Urogalba 
having the middle pair of tail-feathers elongated, while in the others the tail is 
short and squared; the three-toed jacamars ( Brachygalba ) being notable for the 
feature from which they take their name. In these jacamars the prevailing colour 
of the plumage of the upper-parts is in most cases bronzy or metallic green. The 
green jacamar ( Galbula viridis ) is the best known species of the family, and is 
