Rostrum clearly distinct from melon, insertion angle of melon onto beak approaches 75 degrees.

Rostrum is elongate with an exaggerated undershot jaw.

Mandible extends anteriorly beyond maxilla by more than 5 cm.

Rostrum not distinct from the melon, these features grade seamlessly together.

Rostrum varies from short to medium in length, jaw is only slightly undershot.

Mandible extends anteriorly beyond maxilla by less than 5 cm.