18 Proceedings of the Biological Society of Washington. 



II, 1859, 67 (list of species). — Sclater, Proc. Zool. Soc. London, 1860, 

 465 (crit.; list of species). — Gray, Hand-List Birds, I, 1869, 359, part 

 (syn.; list of species). — Giebel, Thes. Orn., II, 1875, 662, part (syn.; 

 list of species).— Sclater, Cat. Birds Brit. Mus., XIV, 1888, 198, 

 part (syn.; monogr.;). — Waterhouse, Ind. Gen. Avium, 1889, 139 

 (references). — Sharpe, Hand-List Birds, III, 1901, 131, part (list of 

 species).— RiDGWAY, Bull. U. S. Nat. Mus., No. 50, IV, 1907, 486 (syn.; 

 diag.; key to forms). 



Early references to the birds of this group are comparatively few in 

 number; they appear under the generic names Muscicapa and Muscipeta. 

 Spix in 1825 described a member of the genus (as now understood) under 

 the name Platyrhynchus xanthopygus, but the generic name be used had 

 long been preoccupied. Two years later Swainson formally established 

 the genus Tyrannula, designating Muscipeta ( = Muscicapa) barbata as its 

 type. The same name with a masculine ending had previously been used 

 by Vieillot in 1816, and it is worth while noting that under one of the 

 rulings of the International Commission on Zoological Nomenclature this 

 use would not invalidate Swainson's name, which would thus become the 

 proper designation for this genus. There seems to be a general disposition 

 to ignore this particular ruling (a movement in which we concur), and under 

 the circumstances we therefore pass on to Myiobius, which was first used 

 by Darwin in 1839. Darwin here attributes it to Gray, and gives it ?s a 

 substitute for Tyrannula of Swainson. This is fortunate, inasmuch as its 

 type is thus the same as that of Tyrannula, and not one of the four species 

 arranged under it at this place, none of which are now recognized as properly 

 belonging to it. The case is parallel to that of Pachyramphus, a few pages 

 farther on in Darwin's work, to which Dr. Richmond has already called 

 attention (Proceedings U. S. National Museum, LIII, 1917, 568, note). 



As used by Gray in 1845 Myiobius had a wide application, being even 

 extended to include what is now known as Myiarchus. Cabanis, writing in 

 1859, was the first author to restrict it to the three closely allied species 

 which he recognized at that time, while the following year Sclater used the 

 name for these and a fourth species, but in a subgeneric sense only. In 

 Volume XIV of the Catalogue of the Birds in the British Museum he admit- 

 ted no less than twenty-one species under Myiobius, and Sharpe followed 

 him in 1901 with twenty-eight. As used by these authors the genus 

 included such diverse forms as to render its diagnosis virtually impossible, 

 and it remained for Mr. Ridgway to insist upon its restriction to those 

 originally assigned to it by Cabanis and to their immediate allies. As 

 thus restricted the group is sufficiently homogeneous, and may be readily 

 recognized by the following combination of characters: 



Bill shorter than the head, typically Tyrannine, flat, wide at base, with 

 strongly ridged culmen and decurved tip, terminally compressed in vertical 

 outline, the lateral outlines nearly straight and sub-parallel basally. 

 Nostrils oval, in basal half of bill. Rictal bristles excessively developed, 

 reaching beyond tip of bill when directed forw^ard, and feathers of chin with 

 more or less bristly points. Wings moderate, rounded, the tenth (outer- 



