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Show 1899.] CRANIAL OSTEOLOGY OF THE PARROTS. 21 with a very short free extremity, and the fossa for the temporalis muscle is seen to extend upwards behind it, instead of being merely overhung by it as in Psittacus. The squamosal process is well developed, rather long and pointed at the end ; it is somewhat shorter and broader in Lorius than in the others. The posterior ramus of the prefrontal is well developed and extends behind the middle of the orbit; but it does not create a suborbital ring, though, especially in Trichoglossus and Eos, it may come very near to the squamosal. The posterior wall of the tympanic cavity is formed after the fashion of Psittacus, but leaves an aperture of an apparently different shape, by reason of the greater forward growth of its middle portion, so that the crescentic form of the aperture, or rather the development of a conspicuous notch below and another above and posteriorly, is better marked. The latter or upper notch is just below and behind the suprameatal tubercle. The anterior wall of the tympanum shows (in all four genera) au ascending bar or splinter of bone that walls off from the tympanic cavity the articulation of the quadrate. This is a little point of resemblance to Nestor, but it is the only one I can detect, and unsupported it goes for nothing. The groove or area in front of the suprameatal process is well-marked ; it is very much more extensive than in Psittacus, for it extends into an excavated surface on the squamosal process, reaching well m front of the glenoid notch. The jugular foramen is exceedingly small, and the posterior recess of the tympanum not large. The quadrate has two deeply separated heads ; the inner one is very small and bent inwards almost perpendicularly to the shaft. The two sockets on the squamosal and prootic elements are distinctly and rather widely separate, and the latter is a small deep hollow. The mandibular fontanelle is a minute orifice placed much further back than in Psittacus. The basitemporal ridges are better marked thau in Psittacus, but they distinctly terminate below the foramen for the vagus, and are separated by a notch from the succeeding ridge which marks the under border of the parocci-pital. It is true that both in Nestor and Psittacus there is at the same point a slight change of direction and appearance of discontinuity, but, especially in the former skull, the ridges are nearly continuous. Family CACATUID.E. The Cockatoos possess certain cranial characters in common and their skulls are easily to be recognized, but there are many variations within the family and even within the restricted genus Cacatua. The orbital ring is complete by union of the prefrontal and postfrontal bones, and from the hinder part of the suborbital bar thus formed a strong process runs backwards to fuse, in most cases though not in all, with the squamosal process, and thus (as has been |