252 GENERAL ORNITHOLOGY part ii 



sphenoid, not from its rostrum, articulating with pterygoids very 

 near the posterior or outer ends of the latter ; and head of quadrate 

 with a single articular facet, as in Ratitm. 



Sehizognathism (Gr. orx'tC'^, schizo, I cleave) is the kind of 

 " cleft palate " shown by the columbine and gallinaceous birds, by 

 the waders at large, and many of the swimmers (see' Fig. 77). In 

 this general case, the vomer, whether large or small, tapers to a 

 point in front, while behind it embraces the basisphenoidal rostrum, 

 between the palatines ; these bones and the pterygoids are directly 

 articulated with one another and with the basisphenoidal rostrum, 

 not being borne upon the divergent posterior ends of the vomer ; 

 the maxillopalatines, usually elongated and lamellar, pass inwards 

 over [under, when the skull is viewed upside-down, as it usually is] 

 the anterior part of the palatines, with which they unite and then 

 bend backwards, along the inner edge of the palatines, leaving a 

 broader or narrower fissure between themselves and the vomer, on 

 each side, and do not unite with one another or with the vomer. 

 It follows from this that in the dry skull of a plover, for instance, 

 which shows the schizognathous arrangement extremely well, " the 

 blade of a thin knife can be passed, vrithout meeting with any 

 bony obstacle, from the posterior nares alongside the vomer to the end 

 of the beak." There are several groups of birds which exhibit the 

 schizognathous plan, with ulterior modifications of palatal and other 

 characters, (a) The columbine birds (Peristeromorphce of Huxley's 

 arrangement) : maxillopalatines elongate and spongy ; basiptery- 

 goid processes narrow, but prominent. (5) The gallinaceous birds 

 (AledoromorpJice) : maxillopalatines varying greatly in size, but always 

 lamellar : palatines long and narrow, with rounded- off postero- 

 external angles ; basipterygoid processes oval, flattened, sessile upon 

 the rostrum, articulating with the pterygoids, (c) The penguins 

 {Spheniscomorphw) : maxillopalatines concavo-convex and lamellar ; 

 no basipterygoid processes ; pterygoids flattened, {d) In the gulls, 

 petrels, loons, grebes, and auks, constituting the CecormrphcB, the 

 maxillopalatines are usually lamellar and concavo-convex, but may 

 be spongy, tumid, and closely approximated to the vomer ; and 

 basipterygoid processes are absent or present. («) In the cranes, 

 rails, and their allies {Geranomorplwe), the maxillopalatines are 

 concavo-convex and lamellar, and basipterygoid processes are usually 

 absent. (/) In the plover -snipe group, or limicoline Grallm 

 (Charadriomorphm), the maxillopalatines are always concavo-convex 

 and lamellar ; the basipterygoid processes narrow and prominent. 

 Excepting perhaps group d, which does not hang together so well, 

 the schizognathous groups here noted correspond very closely with 

 recognised orders or suborders of birds ; in all of them, the maxillo- 

 palatines are perfectly distinct from one another and from the vomer. 



