The nomenclature of this region is confusing. The easy part is the Lagoon nebula, or Messier 8. The emission region to the image left has a wide variety of names, but probably best known for the emission/refection region NGC6559. Barnard 303 is the dark nebula "V" shaped region - Barnard's Catalogue of 349 Dark Objects in the Sky (Barnard, 1927).