THE PRINCIPAL BIRD GROUPS 101 



their being kept apart. The remaining Passeres 

 may be conveniently divided into four lesser 

 groups, viz., the Oscines or Singing Passeres, 

 the Oligomyodae or Non-singing Passeres, the 

 Tracheophonae or South American Passeres, and 

 the Atrichornithes or Australian Scrub Birds. 

 The number of families into which each of these 

 sections or groups should be divided, is quite 

 impossible to say, scarcely two authorities agree- 

 ing in this respect. Some systematists admit 

 no fewer than thirty-seven in the Oscines, which 

 includes the Crows, Starlings, Orioles, Finch-like 

 birds, Larks, Creepers, Titmice, Shrikes, Wax- 

 wings, Thrushes, Wrens, Timeline Birds, Fly- 

 catchers, Swallows, and so on. This is by far 

 the most extensive group. The Oligomyodae is 

 made up of eight families, and includes such 

 forms as the Tyrant Birds, the Manakins, the 

 Cotingas (which includes the curious Umbrella 

 Bird and Bell Birds), the Plant-cutters, and the 

 Pittas. The Tracheophonae consists of three 

 families, the Wood Hewers (among which must 

 be numbered the Oven Bird), the Ant Thrushes, 

 and several genera of very aberrant birds classed 

 as the Pteroptochidae. The Atrichornithes com- 

 prise a single family of peculiarly modified birds, 

 having the clavicles or furcula rudimentary. It 



