OCR Text |
Show 1899.] CRANIAL OSTEOLOGY OF THE PARROTS. 25 auditory meatus in both is wide, and its posterior border concave. The paroccipitals are prominent, pointed, and directed backwards, without forming the transverse projection and ridge of Licmetis. The basitemporal ridges run nearly continuously on to the paroccipital, and the surface external to them is inclined outwards. The shaft of the quadrate is very stout. In Callocephalon the two heads of the bone are only separated by a very narrow and shallow groove. In both genera the angle of the mandible is rounded and truncate. In Microglossa the squamosal process fails to join, though it projects a little way under, the suborbital ring; it is exceedingly small and pointed. The posterior or postorbital region of the suborbital bar is very large and broad, and sends back a posterior lobe from its lower angle. The temporal fossa is very small, scarcely larger than in G. roseicapilla and much less than in G. leadbeateri. The auditory meatus is wide open, its aperture approximately oval. The paroccipital process is large ; looked at from behind its posterior border is nearly vertical, but its angle projects somewhat posteriorly ; it is very little hollowed within, and the jugular foramen is very small; the basitemporal ridges run almost uninterruptedly into the deeply compressed lower border of the paroccipital. The articular facets for the quadrate are separated by a well-marked groove, and are walled off from the tympanic cavity by a splinter of bone. The quadrate has two deeply separate heads, the inner one scarcely half the size of the outer; its other characters are those of the family ; the extra facet below the quadrato-jugal cup is small and deeply marked. The angle of the shaft is short and bluntly pointed ; the mandibular fenestra is obsolete. In the skull the inner wall of the orbit is scarcely perforate in front of the orbital foramen ; the jugal bone is notably expanded at its anterior end. The skull of Calopsittacus (fig. 17) is similar to that of the Fig. 17. Calopsittacus novm-hollandice (enlarged). Cockatoos in having the orbital bar completed by junction both with postorbital and with squamosal, which leave between a rather elongated supratemporal vacuity. The auditory meatus is narrower than in the Cockatoos, and its posterior and inferior notches are |