16 PEOF. d'aecy w. THOMPSON ON THE [Jan. 17, 



this point to the outer mai-gin of the paroccipital ; (3) springing 

 from the upper of the two supra-occipital ridges, a little way before 

 they reach the tubercle and merge together, a ridge curves down- 

 wards to another tubercle (s.m.) at the upper and hinder corner of 

 the meatus ; and (4) from this latter tubercle a ridge is continued 

 towards the inferior border of the squamosal or zygomatic process ; 

 the temporal fossa is bounded above by (5) the great curved line 

 which runs from near the base of the line called 3 to the apex of 

 the postorbital process. These lines separate the followiug areas 

 or fossie : I, a narrow triangular area, posterior to the auditory 

 region, which gives origin to the main body of the digastric ; II, the 

 temporal fossa, and III, the small space below the line marked 4, 

 which gives origin to the second portion of the digastric muscle. 

 In the Grey Parrot (fig. 5) we can distinguish all these lines and 

 intervening areas ; but the digastric area is much broader than in 

 the Eaven, owing to the greater extension forwards of the thin 



Fig. 5. 



d. 

 ,m 



Psittacws erithacus, for comparison with fig. 4. 

 (Letters as iu previous figures.) 



posterior w'all of the meatus, and the temporal fossa is much 

 longer and narrower. The line 3, between the digastric and tem- 

 poral fossae, guides us to its termination in the suprameatal process 

 of Mivart, which is thus seen to correspond to the tubercle we 

 have marked s.m. in the Raven, in which bird it is some distance 

 behind the glenoid cavity, the intermediate space constituting our 

 fossa III. This last and smallest fossa is excessively small in the 

 Grey Parrot (fig. 6, p. 17), being only represented by a groove 

 between the suprameatal tubercle and the little process of the 

 squamosal internal to it, which descends for a very short distance 

 external and posterior to the head of the quadrate — in other words, 

 which bounds the inconspicuous notch over the head of that bone. 

 To return to Nestor (fig. 6), a comparison of the same clearly marked 

 impressions shows us a still larger digastric and smaller temporal 

 fossa, and leads us to recognize the suprameatal process iu that 

 one which is now separated widely from the glenoid cavity by the 



