The plane of the narial rim is oblique to the lateral surface of the maxilla.
The narial passage is freely open, maxillo-turbinals not being developed.
The internal or nasal surface, like that of the premaxillae, is excavated by a deep longitudinal groove, the narial passage.
Corresponding with the clumsy nose are very short nostrils, the commencement of the narial aperture being therefore very far back.
This means that there is a factor that inhibits the development of the narial flap.