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Show 40 MR. W. P. PYCRAFT ON THE [May 2, iii. TnE S kull of the N estling. (PI. II. figs. 1 & 1a-) It is a matter for regret that the British Museum Collection of nestling skulls of Eurylsemidse is limited to half-grown specimens of Eurylcemus ochromelas, and these have suffered somewhat severely as a consequence of having been preserved in formol. a. Gartilage-bones. The basioccipital cannot, in these skulls, be more than imperfectly traced, having become fused with the lateral occipitals. The exoccipital, or lateral occipital, is a large, more or less linguiform plate presenting a broad convex external border, the inferior segment of which forms the tympanic cavity, while the superior arc of the curve is applied in part to the base of the squamosal and in part to the parietal. It is bounded mesiad by the supraoccipital and the occipital foramen, which excavate a considerable moiety from its internal border. Inasmuch as the exoccipital comes into contact with the parietal, it resembles that of the Cuculidse. The supraoccipital is short antero-posteriorly, and is not yet ossified ; its superior margin being W-shaped and leaving a large fontanelle between itself and the parietals. Laterad it has fused with the lateral occipitals, leaving only a faint tell-tale notch to indicate the junction. The pro-, epi-, and opisthotic bones are now completely concealed when the skull is viewed externally. The basisphenoid is also concealed, being underfloored by the basitemporal plate. The alisphenoid appears as an oblong plate, having its long axis horizontal. The orbito-sphenoid is still membranous, while the presphenoid has fused with the basisphenoid. The mesethmoid has only just commenced to ossify, and is represented by a small linguiform plate supporting the yet cartilaginous antorbital plate, and bounded in front by the craniofacial fissure. The interorbital septum formed by the backward extension of the plate is as yet only outlined in cartilage. The olfactory cavities occupy less than half of the so-called anterior narial apertures as seen in the dried skull. The actual anterior nares, in Eurylcemus ochromelas for example, are small and round, and placed at the extreme anterior angle formed by the divarication of the nasal and maxillary processes of the premaxilla. The superior segment of this circle is formed by membrane, and this extends backwards and inwards as a subtubular sheet to be attached to the antorbital plate. Mesially this tube is shut in by the nasal septum, and inferiorly by membrane forming the roof of the palate. Within the chamber thus formed lies a long somewhat spatulate cartilaginous turbinal extending backwards5 by a short stalk, to the anterior end of the vomer. The free end |