1«88.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 173 NOTES ON THE OSTEOLOGY OF THE THRUSHES, MIMING, AND WRENS. BY FREDERIC A. LUCAS. (With Plate xxxvn.) The present paper was commenced more than a year ago, but many circumstances have combiued to prevent its completion sooner. It was undertaken at the suggestion of Mr. Robert liidgway, in the hope of throwing a little light on the relations of the Mimince. This peculiarly American subfamily, formerly placed among the Thrushes, has of late found a resting-place with the Wrens, and in the A. O. U. Check List stands at the foot of the family Troglodytidce, Galeoscoptes standing last of all. I must at the outset confess that it has been a somewhat diffi-cult matter to select for comparative purposes characters that should be at once well marked and of undeniable taxouomic value. Judgiug from an examination of many specimens such characters would seem to be found in the shape of the maxiilo-palatines, pars plaua, costal process, and coracoid. Many bones which might be supposed to offer good points are found untrustworthy when put to the test. Looking down upon two parallel series of Crania, one of Thrushes and one of Wrens, the first will be found to differ from the second in the much greater breadth of the lachrymal region due to the lateral ex-pansion of the pars plana. Viewed in the same way the skulls of the Mimince are seen to be in-termediate between the two, although the Mimince vary somewhat among themselves; Harporhynchm, due allowance being made for its size, having as narrow a skull as the Wrens, while Galeoscoptes and Melanoptila approach, but do not equal, the Thrushes. Another very obvious character for comparative purposes is found in the relative width of the external process of the nasal and the angle sub-tended by this bone and the pars plana. In all the Thrushes examined the external process of the nasal is broad, in all the Wrens and in the Mimince it is narrow. In the Thrushes the angle formed by the nasal and pars plana is very acute, while in the Wrens and Mocking-Thrushes the corresponding angle is more or less open, most so in the Wrens. In these particulars Galeoscoptes comes nearer the Thrushes than do its associates. Aside from the small taxonomic value of the lachrymal it is a most un-satisfactory bone to deal with, not only from its small size but from its delicate texture and the insensible manner in which it merges into the surrounding membrane. This causes the lachrymal to be frequently lost in the preparation of a skull, in spite ot the most watchful care, and
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