1895.] LORIUS PLAVOPALLIATTJS AJTD PSITTACTJS ERITHACTTS. 391 



o£ the inferior margin of the ramus instead of one of about 60° as 

 in P. erithacus. 



On the outer surface of the ramus there are in both species 

 some small foramina, and a rather conspicuous one in P. enthacus. 

 In that species also there is a considerable oval vacuity, or 

 defect of ossification, at about the middle of the ramus dorso- 

 ventrally, the middle of the vacuity being beneath the post- 

 coronoid process. In L. jIavopalliaUis, however, the ramus is here 

 entire but somewhat depressed or concave in this region. This 

 depression is limited behind by a ridge which runs obliquely down- 

 wards aud forrt-ards from the articular process to the ventral 

 margin of the ramus. This is only represented in P. erithacus by 

 a prominence which runs downwards and forwards from the 

 articular process for about half the breadth of the ramus. In 

 P. erithacus a small foramen opens beneath the prearticular 

 process at about one-fourth of the dorso-ventral diameter of the 

 ramus from its dorsal margin. In L. jJavopalliatus it opens a 

 little behind that process and nearer the dorsal margin. Its 

 external surface towards the angular process is slightly concave in 

 both species, rather more so in L. flavopalliatus. 



In L. favopalliatus the inner surface of each ramus presents 

 two elongated concavities separated by a ridge. At its anterior 

 end this ridge curves sharply upwards, being also there most 

 prominent, and approaching near to the coronoid process. Just 

 behind its upwardly bent part a conspicuous foramen leads into the 

 substance of the mandible. At its posterior end this ridge joins 

 the outer margin of the larger articular surface for the quadrate, 

 at the same time bounding externally a small but deep fossa which 

 is situated outside the front part of that surface. In P. erithacus 

 the conditions are similar save that the ascending anterior part of 

 the ridge is the most conspicuous and ascends completely to the 

 coronoid process, and that the foramen behind it is less conspicuous, 

 opening on the front margin of the defect of ossification (which 

 interrupts the internal longitudinal ridge) ; when the defect of 

 ossification is smaller, the foramen opens beneath it. In both 

 species the small foi-amen beneath or near the prearticular process 

 opens into the superior longitudinal concavity of the inner surface 

 of the ramus. 



In both species also the larger articular surface for the quadrate 

 is in the form of an antero-posterior, nearly straight groove. This 

 groove is broadest at its anterior end in P. erithacus, but hardly at 

 all broader there in. L, Jlavopalliatus. On its inner side there is 

 a small surface of bone, broadening gradually backwards, at the 

 hinder end of which is a foramen. This is the innermost part of a 

 subquadrate bony process, the internal articular process (ia), which 

 projects nearly horizontally inwards and supports the outer part of 

 the longitudinal articular groove. 



The smaller and superior articular surface for the quadrate (sa) 

 is on the inner side of the somewhat everted coronoid process. 

 It is nearly straight autero-posteriorly, but strongly convex dorso- 



