The red grouse and the willow-grouse belong to a section or "order" of birds which are classified together because they all have many points in common with "the common fowl" or jungle-cock and the pheasants. That order or pedigree-branch was named by Huxley Alectoromorphæ, or cock-like birds, perhaps more simply termed Galliformes, Gallus being the Latin name for "chanticleer." When there is a question of the groups recognized in the classification of animals, it is well to bear in mind, once for all, that the biggest branches of the animal pedigree are called "phyla" (or sub-kingdoms); that these have branches or sub-divisions which are called "classes" (birds are a class of the phylum Vertebrata). Classes divide into "orders"; these often are subdivided into "sub-orders." Orders comprise each several smaller branches called "families," families branch into "genera," and each "genus" contains a number of "species" which have diverged from a common ancestral form, and become more or less stable and unchanging (but not unchangeable) at the present day. The individuals of a species are distinguishable by certain marks, shape, and colour from the individuals of other species of the genus. They breed true to those points when in natural conditions, and show some differences of habit, locality, and constitution which emphasize their distinction as a separate "species." The order Galliformes of the class Aves or birds is one of some eighteen similar orders of birds. It contains several families, namely, the grouse-birds, the partridges, the francolins (formerly introduced into Italy from Cyprus), the quails, the pheasants, including the common fowl or Gallus, the peacocks, the turkeys, and, lastly, the guinea-fowls. The mound-builders and the South American curassows (very handsome birds to be seen at the Zoological Gardens) are families which have to be separated from the rest as a distinct sub-order. Fifty years ago the pigeons were placed in one order with the galliform birds, which was termed "Rasores," or scratching birds; but they are now separated under the name Columbiformes.