Todd — Studies in the Tyrannidcs. 19 



most) primary shorter than the secondaries, the sixth, seventh and eighth 

 subequal and longest, and with outer webs sHghtly sinuate. Tail varying 

 from about five-sixths of to equal to the wing, even or somewhat rounded, 

 the feathers rather broad, with sub-acuminate tip. Feet moderate, the 

 hind claw about equal to hind toe, the other claws much weaker; outer toe 

 united to middle toe for the whole of its basal phalanx, and inner toe united 

 to middle toe for about half of its basal phalanx. Coloration olive greenish, 

 the pileum (in adult males) with a partially concealed vertical patch of 

 yellow, the rump yellow; tail blackish; under parts yellowish, buffy, or more 

 or less ochraceous. 



As is often the case with such homogeneous genera, the discrimination of 

 the several forms belonging to this group presents a problem of exceptional 

 difficulty, even for the Tyrannidce. Before attempting to present our 

 own views it may be well to give a brief historical resume of the subject. 

 The first species to be formally described was the Muscicapa barbata of 

 Gmelin, 1788, from Cayenne, based on Buffon's figure and account. Then 

 came the Muscicapa mastacalis of Wied, 1821, and the Platyrhynchus 

 xanthopygus of Spix, 1825, both names referring to the bird of Brazil. In 

 1857 Sclater described a third member of the group from Mexico, Tyrannula 

 sulphureipygia, using Swainson's generic name. In the meantime Myiobius 

 had come into common use for the group, as well as for certain more 

 remotely related forms, so that when Sclater described a fourth species from 

 Ecuador in 1860 he called it Myiobius villosus. In 1863 Lawrence pointed 

 out distinctive characters for the Central American bird, which up to that 

 time had passed as barbatus, calling it atricaudiis, but subsequent authors 

 were by no means a unit in accepting this name. In fact, the true applica- 

 tion of the term barbatus, although properly indicated, it is true, by Cabanis 

 in 1859, was not appreciated for many years, due largely to scarcity of 

 specimens, the name being used indiscriminately for several perfectly dis- 

 tinct forms. The resultant confusion in the nomenclature may be 

 imagined. In 1888 we find von Berlepsch describing a sixth species, M. 

 ridgwayi, and Sclater still refusing to admit atricaudus to recognition 

 except as a subspecies, while at the same time confusing "xanthopygius" 

 i=7nastacalis) with barbatus. In 1906 Mr. Hellmayr pointed out charac- 

 ters for separating barbatus, mastacalis, and atricaudus, which he regarded 

 as subspecies, while keeping ridgwayi specifically distinct. Mr. Ridgway 

 in 1907 arranged the forms somewhat differently, keeping "xanthopygus," 

 sulphureipygius, and villosus together as conspecies, and similarly uniting 

 barbatus and atricaudus, leaving ridgwayi to stand by itself. Mr. Hell- 

 mayr in 1911 again insisted that the Brazilian form, mastacalis, had nothing 

 to do with sulphur eipyius. In the meantime a southern race of the latter 

 had been worked out by Mr. Bangs. The next year the present writer 

 described a new form, modestus, allied to atricaudus, from Venezuela, and 

 later on another close ally of the same, suffusus, as well as a very distinct 

 species, serniflavus, both from Colombia. This brings the history of the 

 group down to date. 



With such diverse treatment from leading authorities it is little wonder 

 that the literature of the group is in such a confused state, nor do we flatter 



