TUPAIID^. 113 



occurs in JSylomys and Urmaceus. Posterior to the lowest of these foramina there 

 is another small foramen on the lambdoidal ridge which opens almost directly into 

 the skull in Tupaia and the above-mentioned genera. There is a distinct foramen 

 below and internal to the mastoid process (the stylo-mastoid foramen ?) and internal 

 to it, and on the hinder third of the auditory bulla a small rounded foramen with 

 well-defined osseous walls occurs opposite to the middle of the occipital condyle, and 

 interrogatively mentioned by Mivart as the carotoid foramen, which it is in all proba- 

 bility. Posterior and slightly external to it, and internal to the posterior extremity 

 of the auditory bulla and the mastoid, is a rather large foramen formed by the arching 

 over of the inferior external angle of the occipital to these bones, and constituting 

 th-Q foramen lacerumposterim^-whidi is directed upwards and slightly backwards 

 as a short bony canal. Internal and slightly posterior to it is the anterior condy- 

 loid foramen. Between the auditory bulla and basi-occipital there is a rather long 

 groove running above the carotoid foramen, forwards from the opening of the fora- 

 men jugulare, ultimately forming a closed canal foramen lacerum amterms between 

 the bulla and basi-occipital and basi-sphenoid. The foramen ovale is situated at the 

 middle of the anterior aspect of the bulla, and is formed externally by that bone and 

 the sphenoid, the former constituting the under margin of the opening. External 

 and slightly posterior to the foramen ovale, anterior to the base of the tympanic plate, 

 between the squamous and the bulla, there is a minute foramen, or rather fissure, in 

 the position of the fissure of Glaser. At the anterior wall of the bulla, immediately 

 internal to the foramen ovale and on a lower level, is a round foramen which escapes 

 observation unless the skull is held sideways. It passes directly outwards and back- 

 wards, and a fine wire passed through it comes out at the meatus auditorius externus 

 in a macerated skuU. The external pterygoid plate is perforated by a canal at its 

 base. Anterior, internal, and superior to the forward termination of this canal, is the 

 foramen rotundum, separated by a marked interval from the sphenoid fissure which is 

 directed outwards, forwards and upwards, and separated from the optic foramen by a 

 narrow spicule of bone. There are two foramina external to the sphenoidal fissure, 

 the most external the being smaller. The infra-orbital foramen opens internally 

 at the most anterior portion of the lower angle of the orbit, and the external orifice is 

 0-20 of an inch in advance of it. The lachrymal canal opens rather external than 

 internal to the orbit below the backwardly projecting process at the anterior margin 

 of the orbit, above which there is also another small foramen leading into a canal 

 opening into the nasal cavity. The posterior palatine foramen is at some distance 

 external to the orbital opening of the infra-orbital foramen ; and the anterior palatine 

 foramen is still larger. 



The longitudinal ramus of the mandible has a long, gentle, downward and 

 upward curve as far forwards as the second premolar, anterior to which the alveolar 

 border shows a sHght downward curve. The dental portion of the jaw is laterally 

 compressed, but the portion at the base of the ascending ramus is contracted, and 

 more or less rounded. The coronoid process is directed upwards and backwards, and 

 its posterior margin overlooks the condyle, from which it is distinctly removed, the 



p 



