In the North American Orioles the _baltimore_ and _bullocki_ have the tail but little graduated; _spurius_, more so; the others very decidedly graduated. The bills of the two first mentioned are stout and nearly straight; that of _I. melanocephalus_ quite similar. _I. parisorum_ has the bill more attenuated, but scarcely more decurved; in _spurius_ it is attenuated and decurved, much as in _wagleri_; this character is strongest in _I. cucullatus_. The much graduated tail is combined with a slender decurved bill in _I. cucullatus_ and _wagleri_; with a straighter one in _parisorum_; with a thick, nearly straight, one in _melanocephalus_. The arrangement, according to the graduation of the tail, would be _baltimore_, _bullocki_, _spurius_, _parisorum_, _wagleri_, _melanocephalus_, and _cucullatus_. According to stoutness and curvature of bill, it would be _baltimore_, _melanocephalus_, _bullocki_, _parisorum_, _spurius_, _wagleri_, and _cucullatus_. All the species have the rump and under parts yellow or orange. All have the head entirely black, except _bullocki_, in which its sides are orange, and _cucullatus_, which has an orange crown. All have black on the throat. In the species with black head and neck, all have the tails black towards the end, except _bullocki_ and _baltimore_. The females and young males are so entirely different in colors from the adult males, and so similar in the different species, that they can best be distinguished by the details of form and size. The _I. prosthemelas_ and _I. melanocephalus_ are placed, according to the above arrangement, in different subgenera, yet the young male of the former and the adult male of the latter are so perfectly similar in colors as to be undistinguishable in this respect, and require careful examination of points of external structure to be separated (see description of _I. melanocephalus_, p. 782). The following synopsis may help to distinguish the North American Orioles and their nearest allies, as far as color is concerned. [34] An attempt at division into subgenera is as follows:— _Icterus_, bill stout, conical, the culmen and gonys nearly straight. Tail graduated. Species: _vulgaris_, _auduboni_, _melanocephalus_. _Xanthornus_, bill slender, slightly decurved. Tail graduated. Species: _wagleri_, _parisorum_, _spurius_, _cucullatus_. _Hyphantes_, bill stout, conical; the culmen and gonys straight. Tail slightly rounded. Species: _baltimore_, _bullocki_, _abeillei_. We do not find, however, that these subgenera are very tangible, excepting _Hyphantes_, which is rather well marked by square tail and straight outlines of the bill, as indicated above. The differences are really so minute, and the characters so variable with the species, that it seems entirely unnecessary to subdivide the genus. Species and Varieties.