HYEACOTHEEIUM. 637 



below, and the former is angiilate on the middle line for a short distance. 

 The zygomatic arches are not expanded, and are much compressed, with 

 flat external and internal faces. The ptyerygoid alae are deep, and support 

 prominent acute hamular processes. Below these there is a longitudinal 

 ridge on the external face, and still posterior is another external posterior 

 ridge situated- near the alisphenoid bone, which sends a branch downward 

 at nearly a right angle from its anterior extremity. The sphenoid descend- 

 ing ala originates opposite the middle of the glenoid facet. The maxillary 

 bone does not project much behind the last molar tooth. The palate is 

 injured so that the depth of the notch cannot be ascertained. The side of 

 the face in front of the orbit is injured on both sides. There is a lachrymal 

 tuberosity on the anterior orbital border. The ascending branch of the 

 premaxillary grows wider upward The borders of the nasal bones are 

 decurved more and more, posteriorly from a flat apex. Viewed from above 

 the apex is rounded, and the lateral outline gently convex. Their common 

 median suture is distinct. 



The infraorbital foramen is above the anterior border of the fourth pre- 

 molar. The other foramina have been generally described under the head 

 of the genus. The condyloid foramen perforates a flat part of the basioc- 

 cipital behind the foramen lacerum posterius, from which it is well separated. 

 The superior border of the foramen magnum is notched. 



The elevated condyle, and full convex outline of the angle, are char- 

 acteristic of the mandible of this as of other species of the genus. The 

 coronoid process is elevated and has a convex anterior and concave poste- 

 rior borders. There is no postcondylar tuberosity or crest, and the outline 

 of the angle extends far behind the condyle. 



The mandibular ramus is compressed. The ascending ramus rises 

 almost vertically a short distance posterior to the last molar. The sym- 

 physis is narrow, and extends to below the middle of the first premolar. 



The inferior canines form part of an uninterrupted series with the incis- 

 ors. The superior canine is separated from the superior incisors by a dias- 

 tema. The first pi-emolar in both jaws is isolated. The second superior 

 premolars have two cusps, and an internal ledge j^osteriorly. The third and 

 fourth superior premolars are similar, the fourth displaying a little larger 



