What is "tolmomyias"

Tolmomyias is a genus of Neotropical birds in the Tyrannidae family. They are notoriously difficult to identify, except by voice. Their taxonomy is complex and it is likely some of the below "species" (notably the yellow-olive flatbill) actually include several species level taxa. The name flatbill is often replaced by the more general flycatcher. They are relatively thickset birds with proportionally large heads and, as suggested by their name, flat bills. All have a primarily yellow-green plumage with distinct edging to the wings, and the crown is often grey.