170 



GENERAL OBNITHOLOGY. 



the gist of dromecognathism; it is exhibited in several ways, (a) In StrutJiio alone, fig. 75, 

 the very short vomer, borne upon the rostrum, articulates neither with palatines nor with ptery- 

 goids, but with the maxillo-palatines ; and the palatines, which are remote from the rostrum, 

 advance beyond the maxillo-palatines, as in most birds, (h) In Bhea, the vomer is as long as 

 usual in birds, and articulates behind with the palatines and pterygoids, but does not join the 

 maxillo-palatines in front ; the short palatines unite with the inner and posterior edges of the 

 thin fi'uestrated maxillo-palatines. (c) In Casuarius and Bromeeus (cassowary and emeu), 

 the long vomer articulates behind with the palatines and pterygoids, and unites in front with 

 the maxillo-palatines ; these are flat, imperforate, and solidly joined to the premaxillas ; the 

 palatines are short, {d) The extinct Dinornis had flat imperforate maxillo-palatine plates 

 uniting solidly with the premaxilla?, and probably Avith the vomer, as in Dronucus. (e) In 

 Apteryx, the long vomer unites with palatines and pterygoids behind ; short broad palatines 



.y'w.x^^ 



, "Emao 



»orp _ 



ft., 



suture obliquely with flat imper- 

 forate maxiUo- palatine plates, 



which unite both w\\\\ premax- 



illary and vomer. (/) The tin- 



amous, Bromeeognathcc (fig. 76) 



' ' have a completely struthious 



palate " ; vomer very broad, 



uniting in front with broad max- 

 illo-palatine plates as in Bro- 



mcEus; behind articulating with 



posterior ends of palatines and 



anterior ends of pterygoids, both 



of which are thus prevented, as 



in all RatitcB, from any extensive 



connection with the rostrum ; 



basipterygoid processes springing 



from body of sphenoid, not from 



its rostrum, articulating with 



pterygoids very near the pos- 

 terior or outer ends of the latter ; 



head of quadrate with a single 

 skull of tiiiaraou ( Tinamus articular facet, as in Eatitce. 

 rohiistn^i); copied by Shufeldt 

 from Huxley. Letters as he- 

 tore; Mxp, maxillo-palatine. Schizognathism (Gr. crxiC'^, f^cMzo, 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)- lu 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 borae u{)on the divergent posterior ends of the vomer ; 

 the maxillo-palatines, usually elongated and lamellar, pass inwards over {under, when the 

 skuU 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 DJUTOwer 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 weU, " the blade of a thin knife can 

 be passed, without 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 sehizo- 

 uuathous plan, with ulterior modifications of palatal and other characters. (a) The colum- 



Dromceognatlious 



Fig. 77. — Schizognathous skull of 

 common fowl, nat. size, from nature, 

 by Dr. R. W. Sliufeldt, U. S. A. Letters 

 as before ; Pa, palatine. 



