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Show 914 DR. R. W. SHUFELDT ON THE OSTEOLOGY OF THE [Dec. 1, and, as we know, it is pretty well represented in nearly all parts the world. Structurally, on the one hand, their relationship to the Owls is very close, through Podargus and Steatornis. Opportunity has not been afforded me to pick up the other end of the thread, but I am very confident that their affinity with the Swifts is anything but a near one. With the exception of a few minor points in their organization, the Swifts are essentially modified Swallows, and, as the family Cypse-lidae, they belong, in the order Passeres, next to that group. The fact, that in common with Humming-birds, so far as we know the structure of these latter, they have a short humerus and an entire, unnotched xiphoidal extremity to the sternum, is no more reason that the two groups should be classed together, than Talpa and Ornithorhynchus should be for like resemblances. Such similarities are due to physiological adaptation of structure, referable in the present instance to the pecular flight of these birds, and the consequent requirements of the muscles involved in it. Moreover, our investigations above have shown really how verv different these parts are when they come to be carefully compared. So far as the skeleton goes, and it is usually supported by associated parts, the entire summation of the truly fundamental characters of the genus Trochilus are at great variance with the corresponding ones in the skeleton of Cypselus, and militate against the propriety of retaining such forms closely associated together in the same group. The anatomy of the Humming-birds is not as yet sufficiently well known for us to exactly define their position in the system ; but if we may be permitted to judge from the skeleton of Trochilus, there is no reasonable doubt that the extraordinary characters it presents fully entitle these birds to a group by themselves, as an order T R O C H I L I. Morphologically (and morphology is really the only guide, when properly interpreted, that we possess, to natural taxonomy) such a group, I think it will be found, can be fully as well characterized as the Psittaci are, and rested upon fully as firm a foundation, and equally as well circumscribed. It would contain upwards of 500 species, which is very considerably larger than the order containing the Parrots. At the present time I am not prepared to say much about the affinities of this group, as 1 should first like to examine a number of Old-World forms before advancing an opinion. N o little significance, however, attaches to the facts brought to light through the dissections of the Trogonida by the late and lamented Forbes (P. Z. S. 1881, p. 83G), showing the construction of the palate in these birds. It will be seen from the figure this author presents of Pharomacrus mocinno in the work referred to, that the maxillo-palatines in this Trogon are well separated in the median line, that the vomer is long, free, and slender, and that the palatines nowhere come in contact with each other, and are far apart behind. All this agrees with Trochilus, and I only regret that I have not at hand a few skeletons of different Trogons to" further compare these birds with the Humming-birds. |