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Show 312 MR. W. P. PYCRAFT ON THE [Apr. 15, being much reduced and widely separated, but, nevertheless, bridging the palate ; and this by means of a pair of strap-shaped processes, arising from their inner dorsal borders, and extending mesially to meet a horizontally expanded plate developed by the inferior border of the ossified hinder end of the nasal septum. These processes-the anterior septo-maxillary spurs of Parker- feebly developed in Rhinochcetus and Tetrapteryx, are well seen in Psophia (PI. X X X I I I . fig. 8 ); and Mr. Beddard was, I believe, the first to point out their homologies and the part they play in the formation of the peculiar palate of the Cathartae. Thus, in describing the palate of Psophia he says, " If these processes were to be increased in size and to meet a bony internasal septum, we should have the 'desmognathous' skull of the American Vultures." It is possible, that at the time Mr. Beddard did not quite grasp how nearly the Psophiine skull approached the realization of the modifications peculiar to the Cathartae, since I gather-from his silence on the point-that there was no trace of an ossified nasal septum in the skull or skulls which he examined. In all the skeletons at the Natural History Museum, save one, there is no septum, which has apparently been lost in maceration. In this one, it takes the form of a greatly fenestrated plate tapering forwards to a point, and terminating at the distal fourth of the external nares. The fenestration in this species is so extensive that only the hinder end and dorsal border are left, but the hinder end dips downwards so as nearly to touch the maxillo-palatine processes. If this septum developed a horizontal plate, as in the Cathartse, we should have the same type of desmognathism which is now peculiar to the last-named group. The nasal septum of the Cathartae is more reduced anteriorly than in Psophia, never extending forwards beyond the posterior third of the external narial aperture (in the skeleton), and in some genera is not even visible on a side view of the skull. In Pseudogryphus and Catharistes it may be studied to best advantage. In the former it extends nearly as far as the middle of the narial aperture, and is fenestrated much as in Psophia. The bony tissue which in Pseudogryphus forms the anterior border of the fenestra is wanting in Catharistes, so that the septum is invisible when the skull is seen from the side, but, when viewed from below, the sutures between the horizontal plate of the nasal septum and the septo-maxillary spurs are plainly visible. Mr. Beddard, in pointing out the nature of the Cathartine palate, and the probable source from which it was derived, has given us the key to a very important problem-the origin of the Falconiform stem. The Cathartse are the least specialized members of the group, and, it is interesting to note, are also N ew World forms like Psophia. But the low generalized position of the Cathartse is shown as well by other portions of the skeleton as by the skull. W e may, I think, safely regard the Cathartse as the most primitive of the Falconiformes. The importance of a correct understanding of the evolution of |