14 ELEMENTARY SKETCH OF THE OSTEOLOGY OF BIRDS. 



Shizognathous birds into two main sections, from characters 

 afforded by the nasal bones. In the first of these sections, which 

 is known as Schizorhinal (split-nasals^, and which includes 

 among others the Pigeons, Sand-grouse, Plovers, Snipe, Gulls, 

 Cranes, and Auks, the posterior border of the nares is not 

 rounded, but apparently formed by the divergence of two 

 bony bars, which inclose an angle between them ; these bars 

 appear to be processes of the nasals. In the second of these 

 sections, which is known as Holorhinal, (entire nasals) and which 

 comprehends among others the Petrels, Divers, Fowls, Rails, 

 Bustards and Cariamas, the posterior border of the nares is 

 rounded, and the nasal bones do not present the appearance of 

 two distinct splints enclosing an angle. 



I may also add that Professor Parker does not use the group 

 Desmognathse, but classes the birds forming that group, to- 

 gether with the Woodpeckers, (which Huxley classes with the 

 iEgithognathse) in a group which he calls Saurognathae, 

 freptile-jawed). 



Hyoid arch* — The hyoid arch, which supports the tongue, 

 contains a basi-hyal, and two pairs of cornuaf one larger than 

 the other ; these coi'nua never unite with the periotic element 

 of the skull. In the Woodpeckers, the posterior cornua are 

 enormously developed, and curve over the back of the skull 

 towards the frontals, which are grooved to receive them. 



Sclerotic.^ — Though not strictly belonging to the true skele- 

 ton, it may be noticed that birds are provided with a chain of 

 overlapping osseous plates within the sclerotic of the eyeball. 



The vertebral column^. — The vertebral column of a bird 

 (pi I. ev. to ex.) is divided into a cervical || region (cv.), in 

 which the vertebrae do not carry ribs which articulate with the 

 sternumTI Cst.) ; a dorsal** region (dv.) which comprehends 

 all the vertebrse behind, and including the first one which car- 

 ries ribs articulating with the sternum, as far as the sacrumff, 

 the sacral region (sm.) which consists of a number of 

 anchylosed vertebrse, probably corresponding to the lumbar J J, 

 sacral, and anterior caudal§§ vertebrse of mammals, and 



* Hyoid from U. and If cos likeness, named from the U.-shaped form of the human 

 hyoid. 

 f Cornua, from cornu, a horn, applied to the slender processes of the hyoid bone 



J Sclerotic (from <r/cA7;pos, solid,) the outer coating of the eye. 

 § Vertebral column, derived from vertebra a bone of the back, which is again 

 derived from verto, I turn. 



II Cervical, from cervix, the neck. 



% Sternum, from srepvov the breast ; in anatomy applied to the breast bone. 

 ** Dorsal, from dorsum, the back. 



ft Sacrum, applied in anatomy to the vertebrae articulating with the ilia (q, v.) 

 the name is derived from the fact that this part of cattle was offered in sacrifice. 

 XX Lumbar, from lumhris, the loin ; connected with the loins. 

 §§ Caudal, from cauda, the tail. 



