TO BIRD-ANATOMY AND CLASSIFICATION. 191 



posterior terminations of the nasal processes of the praemaxillae." This 

 simply concave nature of the posterior margin of the osseous external 

 nares, as well as the relations of the extremities of the nasal bones to 

 those of the nasal processes of the praemaxillae, is shown in the subjoined 

 figure of the Fowl's skull (see fig. 1). 



In a large number of birds, however, the condition of things is Ibis, 1881, 

 different, as will be evident from an inspection of a similar view of a P e 4 * 

 Gull's skull (Larus argentatus). 



Here (see fig. 2) the posterior margin of the osseous nares has a 

 distinctly slit-like or triangular form, instead of being simply concave ; 

 hence the birds presenting this peculiarity, which varies to some extent 

 in the degree of its development in different forms, may be called 

 " schizorhinal" In most of these schizorhinal forms the line joining the 

 posterior extremities of the nostrils passes behind, instead of in front of, 

 the ends of the nasal processes of the praemaxillae. When the beak 

 becomes shortened and broad at the base, however, as, e. <?., in the 

 Pteroclidae, this feature nearly disappears. Birds belonging to the 

 schizorhinal group are nearly all, with the exception of Platalea and Ibis, 

 " schizognathous" as regards their palate. The " SchizorhinsD " comprise 

 the following minor groups : Columbidae, Pteroclidse, Turnicidae, Parridae, 

 Limicolae (except (Edicnemus, which is holorhinal, therein agreeing with 

 the Bustards), Laridse, Gruidse, Eurypygidse, Rhinochetidse*, Plataleidse 

 (the Hemiglottides of Mtzsch), and Alcidse. Aramus also, as shown by 

 Prof. Garrod's later investigations t, must be included here, being 

 schizorhinal, like the Cranes. All these birds, it may be noticed, belong 

 to the Homalogonatous series, possessing, at least normally, the ambiens 

 muscle, presently to be referred to. In 1877 Prof. Garrod discovered 

 that a similar conformation of the skull, as regards these bones, obtains 

 in certain of the South-American " Formicarioid " Passeres that is, in 

 Furnarius and some of its allies i (Leptasthenura, Synallaxis, Sclerurus, 

 and Phlceocryptes), as may be seen in fig. 3, where that of Fwnarius rufus ibis, 1881, 

 is represented. Eeferring to this, he says, " It has been my habit to P- 5 - 

 group all the birds possessing a schizorhinal skull in a single major 

 division . . . but the independent development of an identical disposition 

 in the small division of the Passerine birds above mentioned weakens the 



* To these may be added, as I have Prof. Garrod's authority for doing, Mesites, as 

 is shown by M. A. Milne -Ed wards's investigations (v. Ann. Sc. Nat. ser. 6, vii. art. 

 no. 6). The Rallidae, with which that naturalist associates Mesites, are all holorhinal, 

 at the same time that they lack the powder-down patches of Mesites, Rhinochetus, and 

 Eurypyga. 



t P. Z. S. 1876, p. 275. 



\ "Note on the Anatomy of Passerine Birds. Part II.," P. Z. S. 1877, pp. 449- 

 452. 



