| OCR Text |
Show 262 MR. W. P. PYCRAFT OX THE [Mar. 17, forwards into a more or less well-developed spine, the processus zygomaiicus squamosi. The base of this angle serves for the articulation of the squamosal head of the quadrate. This zygomatic process is especially well-developed in Cuculus, Crotophciga, and Geococcyx. It is small in Guira and Coua, for example, and in the Musophagi. The processus articularis squamosi is wanting. The temporal fossa? are never very deep, but they may extend inwards to within a short distance of the middle line. The variations in the extent of these fossre have already been dealt with (supra, p. 260). The trigeminal foramen in the Cuculi lies immediately above the mouth of the anterior tympanic recess, on a level with, and in front of, the otic articular surface for the quadrate. In Turacus this foramen is divided by a median vertical bar of bone. The orbito-nasal foramen (v1) appears to be definite only in Geococcyx. In other Cuculince and Musopliagince the alisphenoidal wall only partially ossifies, and consequently this and other foramina around the optic foramen disappear in the dried skull. The orbits are large, and roofed by moderately broad overhanging ledges formed by the frontals, and to a slight extent by the lachrymals. The orbito-sphenoid does not ossify. The interorbital septum in the Cuculi is generally pierced by a large fenestra, which attains its maximum in Dromococcyx and Centropies. In Crotophaga, Coua, Piaya, Bliamphococcyx, Bhino-coccyx, Bhopodytes, and Zanclostomus, however, the fenestra is greatly reduced. In the Musophagi the fenestra is large in Turacus, small in Schizorhis. I have not had an opportunity of examining other genera. The orbit is bounded in front by the antorbital plate (p. 263). The lachrymal in the Cuculi is moderately large, with subequal supraorbital and descending processes. The form of this bone and its relation to the frontal and nasal bones vary considerably however. In lilt,amphococcyx calorhynchus only, apparently, is it attached merely to the nasals. The orbital process looks entirely forwards, instead of upwards : that is to say, it forms a shield for the front of the eye instead of an overhanging ledge therefor; the descending process is slender. The frontals rest on the inner angles of the orbital process of the lachrymal on either side, and appeal-, in the adult skull, to be cut oft' from the nasals and pre-maxillary process by a sharply-defined groove, which runs across the skull from the hinder edge of the orbital process up the lachrymal on the one side to that of the other, and simulates a nasal hinge. Ehinococcyx curvirostr is apparently closely resembles Bhamphococcyx, but the lachrymal being completely fused with the nasals and the frontal behind it, the precise relations of the various regions cannot be made out. In other Cuckoos, though exhibiting a distinct tendency to form an anterior shield rather than a pent-house ledge, the |
