1899.] CRAlV^IAL OSTEOLOGY OP THE PARROTS. 41 



in a greater or less degree, the two areas become connected, with 

 less or more interruption, by a definite ridge. 



Now in the Parrots the inner or sub-pterygoid condyle becomes 

 so extremely enlarged and so elongated from before backwards, 

 that at first sight it appears to form the entu-e articulation. AVith 

 its antero-posterior extension it has also undergone a downward 

 expansion, while the region of the bone below the jugal cup is not 

 only thereby raised far above the level of the inner (or true) condjde, 

 but at the same time becomes much less prominent in the outward 

 or lateral direction. This is one of the respects in which iitrinr/ops 

 seems to have undergone less modification thau the others, for the 

 region bearing the jugal cup is very prominent laterally and less 

 raised than in the others above the level of the main condyle. 

 We have seen that more or less in all Parrots the edge of the 

 mandible plays upon the side of the quadrate below the jugal cup, 

 and we now recognize that this is not a new aud fortuitous contact, 

 but a more or less obsolete survival of what in Birds in general is 

 one-half of the primitiAe articulation. 



In the Cockatoos, especially in Microglossa, and in the Macaws, 

 this articular facet below the jugal cup is quite distinct, and in 

 Strinqops it is also well-marked and points downwards ; in Mlcro- 

 glussa, where the jugal region of the quadrate is also prominent, 

 though less so, it likewise looks more or less downwards, while in 

 the Macaws and others it lies on a more nearly vertical slope. 



It is more difficult to determine how or to what extent tJie 

 posterior extension of this outer condyle, that we have seen to be so 

 well-marked in many birds, is represented in the Parrots. We might 

 be inclined to imagine, from the manuer in which it sometimes 

 comes, as I have described above, to approximate with the inner 

 condyle, that the large size of the latter in the Parrots was due to 

 a fusion of the two ; but the absence of any change in the relations 

 of the corresponding cavity in the mandible forbids me to thiuk so. 

 I take it that this portion of the quadrate is still represented by 

 that region of the bone immediately behind the pterygoid cup 

 which, reduced or truncated in most Parrots, is comparatively 

 prominent in Stringops. And although this area no longer serA^es 

 an articular purpose, I think we may recoguize it (both in its more 

 highly developed form in Stringops, and in the shape of a smaller 

 tubercle in Ara and Mlcroglossa and of an elevated protuberance in 

 Conurus Sac.) by its relations to the quadrato-jugal cup, behind which 

 it lies, and to the region bearing the main condyle which curves 

 evenly backwards towards it. 



I have already shown that in its complete orbit, formed by a 

 junction oP the prefrontal and postfrontal elements, Slringops is 

 unique among the Old- World Parrots ; its temporal fossa is dispro- 

 portionately large compared with all the rest ; the grooved surface 

 posterior to the squamoso-temporal articulation and overhung by the 

 euprameatal process is by far more developed than in any other 

 Parrot except Nestor, though in this respect Stringops itself is far 

 from approaching that peculiar type, and such resemblance as this 



