Order 1. Protozooid Birds—Tenuirostres.
These Birds present a resemblance to each other, not simply in their mode of feeding, since they are collectively insectivorous, but also in the slenderness of their form, and in the dazzling, varied, sharply defined, and very striking colours of their plumage, as well as in their habits, for they employ their feet and tail usually for the purposes of support, and so climb about the upright stems and branches of trees.
Among them also occur the smallest sized Birds, a fact which, compared with a similar one in the Thricozoa, indicates likewise their lower grade or rank.
Fam. 1. Infusorial Birds, Tree-runners or Creepers.
Bill awl-shaped, three toes in front—Humming-birds, Tree-creepers.
The small size of the Humming-birds seems to render them the lowest in rank of the class, and by this means the system obtains a point of departure, unto which similar forms may be annexed. Their manner of feeding is rather a process of lapping, than an actual snapping with the bill; their food also, which consists of small Beetles and their larvæ, requires scarcely any operation of the bill, so that here the cibarial instruments obviously rank upon the lowest stage, and remind us of the proboscis in Flies, Butterflies, and Bugs.
Fam. 2. Polypary Birds, Woodpeckers.
Bill straight and chisel-shaped, two of the toes directed forwards and two backwards.
The Woodpeckers stand obviously a step higher, because their bill is specially active in seeking out larvæ, and their body is held securely by the toes and stiff tail.