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Show 166 MR. W. K. PARKER ON STEATORNIS CARIPENSIS. [Apr. 2, The culmen of the rostrum in Steatornis is subacute (Plate XVII. fig. 2 ); its dorsal outline forms an almost perfect quadrant, it is somewhat wavy, and drops suddenly near the hinge, which is straight across the skull, and is perfect. The nostrils (figs. 1, 2, e.n.) are in front of the middle of the rostrum, reniform, oblique, and 6 millim. long ; a small alinasal valve, covered by the ossified roof, forms the " hilus " of the kidney-shaped opening. These ossified roof-cartilages (al.n.) are full of vascular borings, which give them a different appearance to the nasals and premaxillaries (n., px.). But the fusion (ankylosis) of these parts is perfect, and so also is that of the ossified septum nasi, with the surrounding bones. That wall has in its middle a large pyriform fenestra, 4 millim. long and 3 millim. deep, a structure more frequent in Aquatic and Grallatorial birds than in the higher Arboreal types. This is one of its aberrant characters ; the inferior turbinal (right and left) remains unossified. Under the bulging alinasal tracts there is a gently concave, wide sulcus, which ends iu an open space between the rostrum and the ectoethmoid (pars plana). At this part of the skull the angles of the maxillaries (figs. 2, 3, mx.) are 20 millim. apart; and close here, in the hollow behind the descending crus of the nasal, the projecting maxillo-palatine (figs. 1-3, mx.p.) is seen, right and left. This lateral rostro-cranial space should be largely filled in by the lacrymal (fig. 1, /.), which is so constantly large with a considerable frontal suture, and a broad supraorbital tract, in the Cuculines generally. Here, however, in Steatornis, it is very small, and is ankylosed to the nasal, forming a small projection, 3 millim. in extent, to the postero-superior edge of the rostrum. This condition of things is very common in such Passeres as possess a small lacrymal; in the Corvidae, Laniidae, and some others it is pupiform and free. In the Woodpecker (Gecinus viridis), and in that marvellously aberrant Fowl, Opisthocomus, the same thing is seen ; the lacrymal being very small, and ankylosed to the nasal. The margin of the rostrum is cultrate, and the dentary edge is separated by a groove from the palatine face of this region; the middle is gently ridged, and this ridge passes into the ossified septum nasi (s.n.), which in its fore half is marked off by a right and left chink. In its hinder half it is higher than, but ankylosed to, the maxillo-palatines (mx.p.), which swell downwards, right and left, and have a notched hinder margin. Between these parts there is another sharp notch, filled in, in front, by the bony nasal septum. The outer notches as well as the inner are in front of the maxillary angles, and the whole posterior palatal margin of the rostrum is thus strongly serrate. The maxillo-palatines (fig. 3, mx.p.) are only moderately high and spongy; under their thickest part the prepalatine laths (pa.) pass forward and are ankylosed to them. The fibrous fore part of the prepalatines reaches as far forwards as the middle of the septum nasi; where they escape from under the maxillo-palatines they are |
