IX. The segmentation and chondrification of the skull of the duck

Abstract

Among the problems presented by the bird’s skull and which we have attempted to solve, are the following :— 1. Why the cartilaginous plate in the orbito-temporal region (Gaupp, 1906, termed it the planum sphenolaterale) separates the first or profundus branch of the trigeminal nerve from the second or maxillary branch; this would be the position of a processus ascendens which the bird does not possess, while a pila antotica, which is supposed to be present in the bird, should be situated in front of the profundus branch; 2. Why the glossopharyngeal and vagus nerve-roots are separated by a cartilage which encloses the tympanic region, and what is the nature of this cartilage; 3. How the olfactory nerve makes its way into the nasal capsule, whether it traverses a part of the orbit, and what happens to the orbital cartilage in this region; 4. Why the internal carotid arteries pass through peculiar foramina in the cartilage on each side of the skull before penetrating into the cranial cavity through the hypophysial fenestra; 5. How the turbinals of the nasal capsule can be compared and brought into line with those of other forms.