1899.] CEANIAL OSTEOLOGY OF THE PARROTS. 29 



antero-posteriorly, while iu the others, as iu A. hyacinthinus, that 

 of each side converges inwards : in the same species the angle is 

 somewhat less truncated than in the others, and the facet for the 

 insertion of the depressor muscle smaller, more rounded, and not 

 ascending, as in the rest, on the posterior margin of the bone. 



The Co]s'ures. 



Excluding the Macaus, I have examined of the other Conuridae, 

 Conurvs, Pi/rrhura, Myopsittacus, and Brotogerys. The skulls of the 

 firsl. differ from those of the last two materially. In Conurus I 

 have found the orbital ring complete ia C. hucotis, but incomplete 

 in C ceruginosus (fig. 21 ) and C. hcemorrhotis : in both of the latter, 

 however, the imperfection is but slight, the prefrontal process 

 running backwards nearly to contact with the postfrontal. The 

 squamosal process is somewhat stout, and curves forward iu the 

 direction of the orbital riug ; its lower border forms a marked 

 notch over the region of vhe quadrate articulation. The auditory 

 meatus is considerably uider in C. luemorrlious than iu ihe other 



Fio-. 21. 



Conurus CBruyinosus. 



two species, and the upper and lower notches are accordingly 

 better marked in the latter. The inner head of the quadrate is of 

 considerable size ; the antei'ior process is very slender ; the posterior 

 angle of the bone is reduced, and the articular surface runs up 

 abruptly to end in a prominence on a level with the base of the 

 shaft, making the outer surface of the bone appear narrower than 

 usual ; but this last character is much less marked iu C hcemorrlious 

 than in the others. The paroccipital wings and basitemporal 

 ridges are well developed. The supra-occipital is markedly tumid 

 in the region of the middle lobe of the cerebellum. The mandible 

 is extremely short and broad, and its fontanelles are obsolete. The 

 descending processes from the hinder border of the maxilla are 

 very well developed in C. JicemorrJious, but not so in the other two 

 species. 



In Pyrrhura Juematotis the orbital ring is complete, as in O. hu- 

 cotis, and the whole skull differs little from the latter species, except 

 that a mandibular fontanelle is present and the interorbital vacuity 

 is unusually large and rounded or less produced posteriorly. 



In Brotogerys and Myopsittacus the orbit is incomplete, and the 



