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Show 1903.] AXD WINDPIPE OF 'ME AMEIUCAX VULTURES. 389 Interrelationships of the Genera CATHARTES, SARCORHAMPHUS, and GYPAGUS. The foregoing remarks upon the windpipe lead to the consideration of the relationships inter se of the American Yultures, Garrod pointed out * the agreement of Sarcorhamphus and Gypagus in possessing the femoro-caudal, which is absent in Cathartes. Pycraft, in an osteological survey of the " Falconi-formes" f, has noted characters, some of which lead him to bracket together Gypagus and Sarcorhamphus, though others do not apparently justify such a juxtaposition. On the whole, it seems to m e to be clear that the skulls of Sarcorhamphus and Gypagus are more like each other than either is to the skull of Cathartes ; and I shall attempt to justify this view by calling attention to a few minutiae which have not been dwelt upon in this connection. The outline of the skull, as seen from the side, is very characteristic. Cathartes has, relatively speaking, a long low skull with a proportionately longer maxillary and premaxillary region; it is almost Cormorant-like in aspect. In the other two genera this region is deeper and shorter and descends with more of a curve, instead of possessing an upper contour-line which is almost a straight line. The premaxillary region, in fact the end of the beak region, is much more inflated in Gypagus and Sarcorhamphus than in Cathartes. The pervious nostrils are of greater length and narrower across in Cathartes than in the two other genera which agree with each other in this feature ; moreover, in Gypagus and Sarcorhamphus the conjoined maxillary plates are visible as projecting forward beyond the posterior end of the nostril, more especially in Gypagus. In Cathartes they are not so visible. On the lateral aspect of the skull another curious though small difference may be noted, which serves to ally Sarcorhamphus and Gypagus and to divide them both from Cathartes. In the last-mentioned bird Mr. Pycraft has correctly figured % a groove which he terms the " nasal hinge," This appears to separate off the lacrymal (fused to the frontal) from the nasal in front. The suture in question is semicircular and with the convexity anterior. In both Sarcorhamphus and Gypagus the hinge is present but has more the form of a half ellipse; moreover, the concavity is forward and it thus appears as if a backward process of the nasal were embraced by the concave anterior margin of the lacrymal. Mr. Pycraft has also figured §, behind the nasal hinge in the same bird, a strong ridge which presumably marks the boundary of the lacrymal, and is prolonged so as to slightly overhang the orbit. This ridge is quite absent in both Sarcorhamphus and Gypagus, the orbital margin of which is here smooth. It must be admitted, however, that, in one point exhibited in this particular region of the skull, Cathartes is rather intermediate between the Condor at one extreme and Gypagus at the other. This is the backward direction of the * Collected Papers, London, 1881, p. 210. + P. Z. S. 1902, vol. i. p. 277. X Loc. cit. pi. xxxii. fig. 1, nh. § Fig. 10. Wrongly ascribed in the explanation of plate; to Serpcntarins. |