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Show 14 PROF, D'ARCV W. THOMPSON ON T H E [Jan. 17, the antero-posterior groove that constitutes the unusually simple glenoid cavity of the mandible. In front of this lower articular margin of the quadrate is a small but distinct rounded bead or condyle for the pterygoid. An anterior process, small, short, and sharply pointed, runs forwards, at an obtuse angle to the shaft of the bone. The shaft has two heads, the external or squamosal one being large, the inner or prootic one much smaller and separated from the outer by a very shallow groove : a pneumatic foramen enters the shaft on its inner side, below the prootic capitulum. A cup for the quadrato-jugal articulation is directed outwards and forwards, and stands elevated on a tubercular mass of bone, whose posterior surface forms a conspicuous ridge; on the sloping ridge below the cup is a small accessory articular surface, which plays against the edge of the mandible (cf Mivart, pp. 374, 391), and whose comparative anatomy is more fully discussed below. W e shall find that the quadrate is markedly different from this in Stringops; and that in the other genera considerable but less important differences exist in the greater or less separation of the two capitula, the size of the anterior process, the distinctness of the pterygoid condyle, and the conformation of the parts adjacent to the quadrato-jugal cup. Family NESTORIDJE. In all the characters with which this paper is mainly concerned the skull of Nestor (figs. 3, 6) is extremely interesting. The orbit is incomplete. The postfrontal process is rudimentary ; the prefrontal process is long, evenly curved, and reaches nearly to the squamosal. The squamosal region is entirely different to that of any other Parrot. The squamosal or zygomatic Nestor notabilis. pj., postfrontal process; sq., squamosal. process, instead of being slender and free on its lower or posterior margin, is continuous with a flattened buttress of bone which connects it with the main body of the squamosal, and which descends |