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Show 168 MR. W. K. PARKER ON STEATORNIS CARIPENSIS. [Apr. 2, In the large specimens the basipterygoids have a facet for their perfect joint with the pterygoids 4-5 millim. in extent; these two oblongo-oval condyloid tracts are 8 millim. across in front, and 11 millim. behind ; they are wider proximally than at their articular face, and project 2 millim. at their hinder notched margin. The sphenoidal rostrum is 5*5 millim. wide between their fore part, and 2 millim. over the palatine groove. The pterygoids (pg.) are 11 millim. long, and measure from 1*5 millim. to 2*5 millim. in breadth. They approxmiate at a few degrees more than a right angle ; in the Trogon, at a few degrees less; this greater divergence is due to the general extension in breadth of the hind skull ; and the same thing is seen in Owls. The fore part of the pterygoid is oblique and tridentate, it overlaps the palatine; the epipterygoid forms a low triangle; the whole bar is arched upwards, and the tone is smooth and strong. The facet for the basipterygoid is in the middle of the shaft, and lies mainly outside an ascending flange of the bone, so that it works outside the fixed condyloid facet of the basipterygoid ; it is only two thirds the length of that fixed facet, and moves beyond it, in front and behind. Thus the capsular ligament must be loose and elastic, as in the oblique facets in the mid-region of the neck of Buceros and other Cuculines. The palatines are set on more suddenly to the "rostrum," or upper beak, than in the Trogon, where, however, they are not hinged; they are not hinged in Corythaix; but the jugals are. These latter bones are not hinged in Steatornis(PlateXVII.fig. 3,j) and are very slender; first depressed, where they begin at the fore part of the jugal process of the maxillary, and then compressed, where they approach the quadrate, into which they fit by gomphosis. The hinder part of this jugal bar is formed by the quadrato-jugal (q.j.). The three elements of this feeble cheek are all ankylosed into one elastic needle of bone, which, in the middle, is only 6*5 millim. thick. The quadrate (q.) is a well-formed normal bone, in harmony with the Owl-like breadth of the hind skull; the setting on of the double hinge, or " otic process," is wide and transverse, the inner head being only about 2*5 millim. behind the outer. In the large Strix (Ketupa) ceylonensis these " heads" of the otic process are 12*5 millim. across; iu Steatornis 7 millim.; in Corythaix 5 millim. Relatively to the size of the skull, Steatornis has its otic process nearly as wide as in the Owl. The quadrate has an average " orbital process ; " it is oblique and pedate, and its body is deep and rather square; the cup tor the end of the jugal bar is neat and pedunculate; the knob for the end of the pterygoid is well-formed ; and the inferior condyle, as usual, is double. This latter part has a hinder trochlea looking inwards and backwards, and an anterior oval, convex condyloid tract which is in a line with the oblique pterygoid, aud just reaches its joint, which is a cup and ball. The action of a palate like this is somewhat less rapid, and the parts themselves are much lighter and slenderer, than in many of the Cuculines, or in the Parrots, generally. This part is rather |
