OCR Text |
Show 1905.] OSTEOLOGY OF THE EURYLuEMID.E. 31 presents an undoubted resemblance, in some respects, to the aberrant Procnicis, in others to the Swallows. The following characters will, however, probably suffice:- The beak is of great size, nearly as broad as long, and joins the cranium by a more or less perfect nasal hinge ; free lachrymals are wanting, save in Calyptomena; palate jegithognathous; palatines short, broad, wide apart, and produced backward into prominent spurs; vomer truncated, much reduced and terminating posteriorly in a pair of slender limbs; pterygoids and palatines articulating by means of an oblique joint; maxillo-palatine processes reduced to long slender rods slightly expanding at their termination beneath the vomer; basipterygoid processes wanting; postorbital processes obsolete; squamosal process prominent The Occipital Region. The foramen magnum is cordiform, its apex rising only slightly above the level of the superior margin of the rim of the tympanic cavity. The plane of the foramen inclines downwards rather than backwards, as in the Capitonidse, but not to such an extent as in the Bucconidee. The base of the foramen is not raised above the level of the basi-cranial axis. The supra-foraminal ridge is barely traceable. There is no lambdoidal ridge, such as is met with in the Capitonidfe for example, but the cranium above the occipital foramen presents a fairly prominent cerebellar dome, bounded on either side by a subcircular depression (the supraoccipital fossa). Above this region the skull rises considerably and presents a gently rounded surface. The tympanic wings of the exoccipital are considerably developed to form a pair of downwardly directed plates, the processus alai exoccipitalis inferior, having a convex border and a convex surface with recurved free edge: through these plates the semicircular canals can be faintly traced. The Cranial Roof (PI. II.).-The cerebral rises vertically above the cerebellar dome and is of considerable width, being wider than long. In regard to the position of the cerebral with relation to the cerebellar dome, the Eurylaemidse agree with the typical Passeres and the Cypseli, and differ from the Capitonidw, for example, wherein the cerebral lies in front of the cerebellar dome. The parietal region is marked by a moderately well-defined temporal depression, the " temporal fossa," which, however, does not extend further inwards than the outer margin of the supraoccipital fossa. This is a Passerine feature; in the Coraciiformes these fosste usually meet in the middle line, forming a more or less well-marked sagittal crest. The temporal fossa? in the Eurylsemidae are mainly responsible for the formation of the well-marked squamosal prominences. The interorbital region is marked with a more or less distinct median groove, sometimes with a low ridge. Immediately behind |