. The structure and classification of birds . ed out by Huxley,and, it may be added, to the parrots. That part of thepalatine is only indicated by a not well marked ridge whichis totally absent in Bernicla leucopsis, Chen general direction of the bone, therefore, is oblique ; it isonly near to the attachment with the pterygoids that itbecomes feathered out in a horizontal direction. That, atleast, is the more normal arrangement; for in Mergus thegreater part of the bone has its upper and lower surface co-incident with the horizontal axis. This, too, is the case withBiziura lob
. The structure and classification of birds . ed out by Huxley,and, it may be added, to the parrots. That part of thepalatine is only indicated by a not well marked ridge whichis totally absent in Bernicla leucopsis, Chen general direction of the bone, therefore, is oblique ; it isonly near to the attachment with the pterygoids that itbecomes feathered out in a horizontal direction. That, atleast, is the more normal arrangement; for in Mergus thegreater part of the bone has its upper and lower surface co-incident with the horizontal axis. This, too, is the case withBiziura lobata. The oval basipterygoid facets for articulation with the ■ For osteology see Paekee, On the Morphology of the Duck and the AukTribes, Cunningham Memoirs B. Irish Ac. No. 6,1890, and Shufeldt, On Anseres, P. U. S. Nat. Mus. xi. p. 215. Absent in Cereopsis, Biziura, Cygnus, and Cnemiornis. See Owen, Tr. ix. pt iii. ANSERES 467 pterygoids are placed so far forwards that the anterior endsof those bones articulate with Fig. 224.—Skull of Qtoerquedula crecca. Lateral View. (After Huxley.) Fr^ frontal; iVa, nasal; Pmx, premaxilla ; Fo, vomer ; Pa, palatine: Pt, pterygoid. The vomer is a thin deepish plate of hone which is moreor less jintimately connected with themedian septum and maxillo-palatines infront. The maxillo-palatines are com-pletely fused across the middle line inmany Anseres ( Chen, HymenolcBmus) ;in Biziura and Mergus they come intocontact but are not fused. The latterhas very un-ducklike palatine in that thesomewhat delicate maxillo-palatines divergefrom each other after their junction pos-teriorly as well as anteriorly, the palatinevacuity in front being (for a duck) un-usually extensive. In Chen ccerulescens,indeed, secondary bony growths havealmost completely obliterated this vacuity,a kind of false palate having beenformed. The lacrymal bones are large, havinga considerable length of line of union withthe skull; they are sometimes
Size: 2387px × 1047px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectbirds, bookyear1898
