OCR Text |
Show 1899.] CRANIAL OSTEOLOGY OF THE PARROTS. 33 the temporalis muscle. The squamosal process is broad, deeply notched at its base above the quadrate articulation, and the suprameatal process and the flattened or excavated surface in front of it are considerably developed. The auditory meatus is narrow and crescentic, its upper end forming a deep notch. While this notch approximates to the occipital ridge, lower down a broad surface lies between the latter and the meatus. The paroccipital process is extremely short and blunt. The nostrils are large, the mandibular fenestra very large, and the interorbital fenestra small. The skull of G. nigra agrees in most points with that of C. vasa- But the paroccipitals are shorter, rounder, and more expanded ; the triangle of the basitemporal plate is more obtuse, and it is less elevated from the level of the occipital condyle. The mandible has in both species a very large fontanelle. In Psittacus the postfrontal process is stout and prominent though short, the impression of the temporalis muscle elongated, but narrow from above downwards. The squamosal process straight and narrow, devoid of a notch ; the suprameatal process ill developed ; the auditory meatus moderately wide, its posterior border nearly straight and widely separate from the occipital ridge ; the paroccipital process is prominent; the nostril and the interorbital fenestra are both of moderate size ; the mandibular fenestra is small. Of Dasyptilus pecqueti (fig. 23) I have only an imperfect skull, removed from a skin ; but, as it is, it exhibits characters of con- Fig. 28. Imperfect skull of Dasyptilus pecqueti. siderable interest. The orbit is incomplete, and the prefrontal process even less than in Psittacus. The postfrontal is small, and much as in the latter genus. The squamosal is extremely stout and broad, and bears an accessory process and notch on its lower border. The suprameatal tubercle is minute. The auditory meatus is nearly circular, and is surrounded by a, strong ring of bone, produced below into a small notch or lip; there is no posterior or superior notch, and in front the ring of bone separates, in an unusually complete way, the auditory cavity from the P R O C ZOOL. SOC-1899, No. III. 3 |