972 MR. W. p. PTCRAFT ON THE [DeC. 13, 



form the anterior segment of the circular aperture of the fenestra 

 ovaHs. 



The internal and external nasal processes are of great length ; 

 the former is the longer, and turns inwards at about its middle in 

 the form of a long rod to underlie the nasal process of the preraaxilla. 

 The free border of the posterior, laminate portion of the nasal may 

 meet in the middle line in the form of a rounded carve, or it may 

 be interrupted in this region by the invasion of the interorbital 

 ridge of the frontal, as in Pygoseelis. 



The nasal processes of the premaxilla are cleft to within about 

 one-fifth of the extreme tip of the jaw ; the posterior, free ends of 

 these processes rest upon the mesethmoid ; on either side they 

 ai'e embraced by the nasals. The maxillary process runs above the 

 maxilla, terminating near the middle of the inferior boundary of 

 the lachrymo-nasal fossa. 



The maa-illa is produced forwards into a long slender splint, 

 below the inferior border of the maxillary process of the premaxilla 

 to within a short distance of its tip, thus forming almost the entire 

 inferior border of the upper jaw, and backwards as a somewhat 

 splint-like rod to assist in forming the quadrato-jugal bar. Above, 

 it is bounded aijteriorly by the maxillary process of the preraaxilla 

 and posteriorly above by the jugal, and below by the quadrato- 

 jugal. Its backward extension terminates on a level with a line 

 passing at right angles through the articulation of the pterygoid 

 and quadrate. On the inner side, near its anterior g, on a level 

 with the articulation of the external process of the nasal with the 

 premaxilla, it gives off a curved rod-like maxillo- palatine process. 

 The body of this is excavated to form the antrum of Highmore. 

 These processes curve inwards on either side so as to embrace the 

 vomer between them, though it does not actually touch them. 

 They do not extend back beyond the level of a vertical line passing 

 through the middle region of the lachrymals. 



The jugal is a long slender splint, resting for the most part 

 upon the posterior hmb of the maxilla. It extends forwards, to 

 the junction of the external process of the nasal with the maxillary 

 process of the premaxilla, and backwards, along the outer side of 

 the quadrato-jugal to within about one-fifth of its posterior 

 articular end. The quadrato-jugal is of considerable size, extend- 

 ing forwards to the level of the posterior angle of the inferior 

 pedate extremity of the lachrymal. The precise relations of the 

 bones composing the quadrato-jugal bar can be well seen in 

 PI. LXI. fig. 3. 



The laclirymal is permanently free, columnar in form, with a 

 laminate or flange-like anterior border, and with expanded 

 obliquely placed extremities. Its superior or dorsal end is applied 

 to the under surface of the na?al, and its inner border to the 

 anterior extremity of the frontal underlying the nasals. Generally 

 the flange-shaped anterior border is perforated by a foramen, but 

 this is not a constant character, the foramen being sometimes 

 converted into a notch. In Pygoseelis, Sphetiiscus, and Aptenodytes 



