FOSSIL RErriLES. 



621 



Tile lacrymal is an unusually large bone. It forms most of the 

 anterior orbital margin. Above, it has a long articulation with 

 the prefrontal, and below, a short one with the jugal. Anteriorly, 

 it has a large development which forms the upper margin of the 

 antorbital vacuity meeting the ascending process of the maxilla. 

 Of tne anterior process much is below the level of the general 

 surface of the face, suggestive of the antorbital vacuity having 

 lodged a large gland. 



The prefrontal is a small narrow bone which forms about half 

 of the upper orbital mai'gin. It is bounded above by the frontal 

 and nasal and below by the lacrymal. 



The fi'ontal is a long narrow bone. Behind, it articulates with 

 the parietal and laterally with the postfrontal, and in front 

 with the nasal and laterally with the prefrontal. It only forms 

 a small part of the orbital margin. 



The postfrontal is a small triangular bone which articulates 

 with the frontal, parietal, and postorbital, and forms a small part 

 of the upper orbital margin. 



The postorbital is a triradiating bone. The upper process 

 passes upwards behind the postfrontal and meets the parietal. 

 The inferior process passes downwards and aiticulates with the 

 jugal, partly lying in front of it and forming with it the post- 

 orbital arch. The posterior process is short. It meets the 

 squamosal and forms with it the temporal arch. 



The jugal is also a triradiating bone. The anterior process is 

 the strongest. It forms most of the infraorbital arch, forming a 

 long suture with the maxilla and meeting the lacrymal. The 

 upper process meets the postorbital and forms with it the post- 

 orbital arch. The posterior process is long and slender and 

 forms the zygomatic arch meeting the quadrato-jugal. 



The quadrato-jugal is an angular bone which supports the 

 quadrate and the jugal and binds them together. Above,^ it 

 meets the squamosal. A large foramen is present between the 

 quadrato-jugal and the quadrate near the lower part of the 

 bone. 



The squamosal is small but fairly strong. It maj^ be regarded 

 as a clasping bone which holds together the quadrate, quadrato- 

 jugal, postorbital, parietal, and opisthotic. A small upper 

 process lies in front of the lateral process of the parietal. The 

 relations to the quadrato-jugal and quadrate will be better 

 understood by the figures given. 



The quadi-ate is a long, well-developed bone. Its upper end 

 is firmly ai-ticulated with the squamosal and possibly also with 

 the opisthotic, and also meets the quadrato-jugal. The lower 

 end forms the articulation. There is a large opening between 

 the quadrate and quadrato-jugal. The shape of the bone is seen 

 in the drawings given. 



The parietal is smaller than the frontal. It forms the back 

 part of the upper ci-anial wall and has a postero-lateral process 

 Avhich foi-ms much of the posterior wall of the upper temporal 



