Osteology of Loxomma AUmanni. 41 



The broad channels or fossaa leading to the external auditory 

 openings [the temfporal fossoi) are bounded on the inner side 

 by the squamous and mastoid bones, and, notwithstanding 

 that the skull has been subjected to immense pressure, are 

 still seen to be at a somewhat lower level than those bones. 

 They pass forward for about an inch from the external pos- 

 terior angle of the mastoid, are rounded off outwardly in front, 

 their floor becoming gradually more superficial on the supra- 

 temporal bones ; these constitute nearly the whole of their 

 floor, the narrow parts of which left on the inner sides are 

 supplied by the ossa quadrata. 



External to these fossse, extend broadly outward and back- 

 ward, for nearly 2 inches behind the posterior border of the 

 occiput, the posterior expansions of the sides of the cranium, 

 or extensions of the maxillee. 



Individual hones. — These can be distinguished, with a little 

 trouble, by observing the lines of suture along which they are 

 united. 



The premaxillaries form the whole of the front of the snout, 

 and are firmly united on the median line ; they are bounded 

 behind, on each side of the mouth, by a small portion of the 

 maxillaries, which in part they overlap ; further in, by the 

 nasal orifices, and next by the nasal bones. 



The maxillaries occupy the edge of the upper jaw, from the 

 outer ends of the premaxillaries and the nasal orifices to the 

 suture uniting the malar and quadrate jugals, a distance of 

 9| inches ; they are seen from above as far as a point nearly 

 opposite to the middle of the length of the orbital vacuities. 

 These bones nowhere measure more than | inch in breadth ; 

 behind the broadest part they rapidly become narrower, and 

 form a mere bordering to the jaw, and are only here and there 

 visible from above. Their inner borders unite in front for an 

 inch with the nasals, then for 2| inches with the lacrymals, 

 and further back with the malars. 



They belong mainly to the under surface of the cranium, 

 and will be noticed again in the description of that part. 



The nasals lie immediately behind the middle of the pre- 

 maxillaries and before the frontals ; they are more expanded 

 in front than behind, contributing to keep up the breadth of 

 the muzzle, and occupying the whole space between the nasal 

 orifices ; they are bounded on their outer sides by the maxil- 

 laries, lacrymals, and prefrontals. 



The lacrymals are wedge-shaped and pointed in front, 

 occupying the angles left by the maxillaries and nasals, and 

 are cleft behind, the outer division being larger than the inner, 

 to enclose the anterior angles of the orbital openings. They 



