1899.] CBAIs'IAL OSTEOLOGY OF THE PARROTS. 37 



rot overhang the quadrate, but is excavated to form a deep liotch, 

 which exposes the head of the quadrate bone. In all these forms 

 the intraorbital fissure is large, the descending processes from the 

 hinder border of the maxillae are large also, the inner head of the 

 quadrate is quite distinct, and the mandibular fenestra is obsolete. 



Fig. 36. 



Agapornis roseicapillus. 



In all, the auditory aperture is much narrowed, by the forward 

 growth of the posterior wall of the meatus ; this takes place to 

 the greatest extent in Puh/tdis and Aprosmictus, in which last the 

 aperture is reduced to a curved slit. The basitemporal triangle is 

 very small in Pi/rrhulopsis, and well defined from the ai'eas at its 

 sides ; the paroccipital processes, looked at from behind, are nearly 

 vertical ; in Aprosmktus they are more horizontal, and the lateral 

 areas are accordingly more on a level with and less defined from 

 the basitemporal ; in Pohjtelis the same tendency is still more 

 displayed. 



In Agapornis the orbital ring is incomplete and the postfrontal 

 extremely small, as in the forms last described. There is a notch 

 at the base of the squamosal process, but the latter is not separated 

 by a groove from the suprameatal ; the conformation here is more as 

 in Eclectus. The auditory meatus is narrow, and the intraorbital 

 vacuity very large. The mandibular fenestra is large also. The 

 quadrate is veiy delicate in form; its two heads are fused, its 

 shaft is very slender, and its anterior process small. 



Family Platycehcin^. 



Of this group I have examined skulls of Flatycercus (fig. 37), 

 Nanodes {Lathanins) discolor, Neophema pulchella, Pnephotas, NijihjjMj. 



Fiff. 87. 



Platycercus eleyans. 



