The zygomatic arch is always complete, and in many cases the jugal extends back to form part at least of the glenoid surface for articulation with the mandible. In _Coelogenys_ the jugal and maxillary portion of the zygomatic arch is greatly expanded and roughened, and the maxillary portion encloses a large cavity. The palate in Rodents is narrow, and the space between the incisor and molar teeth passes imperceptibly into the sides of the face. The anterior palatine foramina form long, rather narrow slits in this region. The bony palate between the grinding teeth is sometimes as in the Hares very short, sometimes as in the Capybara very long. The maxillae extends back beneath the orbit to unite with the squamosal. The pterygoid is always small, but sometimes has a well-marked hamular process which in _Hystrix_, _Lagostomus_, and some other genera unites with the tympanic bulla. The periotic is large, and fused with the tympanic, which forms a prominent bulla, and is generally drawn out into a tubular meatus. The bulla attains its maximum development in _Chinchilla_ and _Dipus_. The mandible is narrow and rounded in front, the two halves meeting in a long symphysis. The angle is generally drawn out into a long backwardly-projecting process, which is often pointed and directed upwards. In the Hares the angle is rounded. The coronoid process is never large. There are a number of points in which the skull of the Duplicidentata (Hares and Rabbits) differs from that of other Rodents. (_a_) The sutures between the basi-occipital and basisphenoid, and between the basisphenoid and presphenoid remain open throughout life. (_b_) Much of the maxillae forming the side of the face in front of the orbit is fenestrated. (_c_) The optic foramina are united to form a single hole, much as in birds. (_d_) The coronoid process is slightly differentiated from the ascending portion of the mandible. The first two of these points have been thought to indicate degradation of the hares and rabbits as compared with higher mammals. CARNIVORA[167]. It is characteristic of the skull in Carnivora that the glenoid fossa is deep, and the postglenoid process (fig. 75, 23) well developed. The condyle of the mandible is much elongated transversely. The orbit and temporal fossa in the great majority of forms communicate freely, the postorbital bar being incomplete.