| OCR Text |
Show 50 MR. W. P. PYCRAFT ON THE [May 2, of those on either side. In section the shaft is subcylindrical. Me. I. is long, as in the Passeres. The pelvic limbs of the Eurylaemidae and Cotingidae can be distinguished from the limbs of the syndactyle members of the Coraciiformes by the fact that, in the latter, the tarso-metatarsus is either broad and flat, or deeply grooved anteriorly, and is more or less triangular in section. Further, the cnemial crests of the tibio-tarsus are, in the Coraciiformes having this type of feet, but feebly developed. x. S ummary. Regarded, by common consent, as the most lowly of the Passeriformes, the Eurylaemidse are at the same time an extremely specialised group ; much more so than has been hitherto recognised. Such a condition might have been expected indeed, inasmuch as this is a common feature among primitive groups. Nowhere is this specialisation more conspicuous than in the skull. The basipterygoid processes have entirely disappeared; the maxillo-palatines have been reduced from broad triangular plates to rod-like splints; and a singularly perfect fronto-nasal hinge has been developed. In some genera, as in Corydon, the beak has vastly increased in size, and has acquired a markedly hooked shape, as well as a great increase in breadth. Nor is this all. The vomer presents a number of gradations in the direction of reduction and degeneracy; and this is true also of the nasals, whereby the anterior narial fossa-which, by the way, is only in fact a narial fossa in so far as its extreme anterior end is concerned- is enormously enlarged. The lachrymal has been reduced to a mere vestige embedded, though still free, in the anterior face of the antorbital plate as in Calyptomena, or it is wanting as in Corydon. The palato-pterygoid articulation is also specialised ; so too is the nature of the vomerine support, this having been transferred from the pterygoids to that of the palatines. The liemipterygoid element appears to be wanting, but traces of this may turn up in the nestlings of Calyptomena. Evidence of yet further specialisation is obtained from a study of the nestling skull. Besides the disappearance of the hemipterygoid just referred to, the squamosal gives unquestionable proof in this direction; yet, at the same time, having preserved the essential characters of its shape, this element, more than any other bone in the skull, affords testimony of no uncertain kind as to the truly Passerine character of the group. Roughly X-shaped, there can nevertheless be no doubt, from the general contours of the bone, that it has been derived from a larger and more conical plate resembling that which obtains in the Corvidae for example. Further, as in all the Passeres, the long axis of this bone is continued upwards and forwards beyond the parietal so as, in short, to overlap the frontal. So far as I have yet been able to ascertain, such an extension does not obtain anywhere amonjj the Coracii- |
