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Show 1 9 0 3 . ] OSTEOLOGY OF THE CUCULIFORMES. 2 6 3 lachrymal extends backwards for some distance over the frentals. In Eudynamys the frontals are deeply notched to receive the orbital process of the lachrymal, which is more or less diamond-shaped. In other genera the orbital process of the lachrymal may be semilunar or rod-shaped. Where the antorbital process is very large, the descending process of the lachrymal is always more or less markedly degenerate. In Cuculus it has disappeared altogether, whilst the orbital process has fused with the frontal and nasal bones. In Zanclostomus javanicus it is reduced to a mere vestige. The descending process is unusually large in Crotophaga, one of the genera, it will be remembered, with a small antorbital process. Geococcyx has the largest lachrymal of all the Cuckoos. It is nearly columnar in form, flattened antero-posteriorly, and deeply grooved immediately above the quadrato-jugal bar. The lachrymal in the Musophagi in its general shape closely resembles that of the Cuculi: the orbital process is, however, inclined more upwards. The descending process, judging from what obtains in Schizorhis and Musophaga, is fairly strongly developed. In Schizorhis the free end of the descending process is twisted in itself, rests upon the quadrato-jugal bar, and articulates by its postero-internal angle with the enormous ossiculum lachrymo-palatinum. The lachry mo-nasal fossa varies considerably in size. Among the Cuculi, it may be described as large in Eudynamys, Centropus, Guira, and Crotophaga. In Coua, Rhamphococcyx, and Geococcyx, for example, it is extremely reduced by the encroachment of the lachrymal. The Ethmoidal Region.-The mesethmoid, both in the Cuculi and the Musophagi, terminates abruptly immediately in front of the antorbital plate. The horizontal plate formed by the expansion of its dorsal border is but feebly developed. The antorbital plate (prefrontal), which, with the lachrymal, bounds the orbit in front, is, in some Cuculi, e. g. Cacomantis, Centropus, Coua, Coccystes, Cuculus, Eudynamys, Geococcyx, Piaya, Taccocoua, and Saurothera, conspicuously large, quadrate in form, and has its dorsal border pierced by two foramina-an inner for the passage of the olfactory nerve, and an outer for the orbito-nasal (v1). In other forms, e. g. Guira, Crotophaga, the antorbital plate, though large, has the external lateral and inferior borders deeply excised. In such cases the orbito-nasal foramen described above is represented by a notch. Attached to the inferior border of this plate is a vestigial ossicidum palatinum, which, however, is generally wanting in dried skulls. In the Musophagi the antorbital plate is greatly reduced, forming but a triangular process projecting from the mesethmoid. From its inferior border depends a well-developed ossiculum lachrymo-palatinum. In Schizorhis this bone is relatively enormous, projecting downwards to articulate by a strap-shaped |
