OCR Text |
Show 1899.] CRANIAL OSTEOLOGY OF THE PARROTS. 11 is then said to be continued into two lateral processes, and it arises, at any rate, very near the meeting-place of the frontal and squamosal, which may very possibly both be found to contribute to its formation. Separated from this postfrontal process by the temporal groove or fossa is the zygomatic process of the squamosal, which it is more convenient to call the squamosal process ; this, in the Grey Parrot, is the larger and longer of the two. It is seen to be slightly indented below near its apparent origin from the skull, and to jut downwards behind the slight indentation (much more conspicuous in certain other forms) which marks the place where the glenoid cavity for the outer head of the quadrate is excavated below. A slight tubercle projects outwards from, or rather behind, the base of the zygoma, behind the glenoid indentation, and is the suprameatal process of Mivart (I. c.) ; between it and the glenoid notch is a small grooved area which in some genera becomes conspicuous. I shall speak of it as the suprameatal area. From the anterior lower margin of the orbit there runs, curving backwards, and crossed near its origin by a well-marked horizontal groove, the preorbital or suborbital process, which represents the posterior process of the so-called lachrymal bone. W e shall find that the relative size of these processes, their fusion or want of fusion to complete or leave incomplete the orbital ring, and the completion of the orbital ring by union of the lachrymal in some cases with the postfrontal, in some also with the squamosal process, furnish us with several important distinctive characters. While it is not the object of this paper to deal with the higher morphological questions, I may point out that the so-called lachrymal bone is (at least in m y opinion), obviously no lachrymal, but a prefrontal (with which in some cases an inconspicuous lachrymal may be conjoined), as nearly as possible identical in its characters and relations with the prefrontal of the Lizards. The bone in a lizard (e. g. Iguana) comes into relation with the frontal, nasal, lachrymal, superior maxillary, jugal, and palatine bones. Its dorsal portion, precisely comparable in most birds to its dorsal ramus in the Lizards, is in relation with the nasal and frontal. Though it does not in any one bird exhibit all the other relations of the lacertilian bone, yet we may discover them severally in one bird or another : in the Snowy Owl, in Balceniceps, and in Podargus it meets or unites with the maxilla ; it comes into relation with the palatine in Struthio and Apteryx ; it meets more or less intimately with the jugal in the Penguins, Petrels, Cormorants, Gypogeranus, and others ; while in the Raven and many other Passeriues, the Penguins, the Guillemots, the Curlew, the Toucan, the Parrots, and many more, it comes into relation with, or fuses with, the ethmoid region, a relation that we cannot seek in the bony skull of the Lacertilia. In Ducks, Geese, and Swans its inferior ramus inclines backwards in the direction of the postfrontal process (the squamosal or zygomatic process being here absent or rudimentary), as it does in the Parrots, and it is said (though I have not actually |